i've put pclinuxos on lower spec than that.  koffice is an ok alternative to open office, but if most of what you do is word processing, abiword will do nicely and it's light. kolourpaint can do a surprising amount and there's also krita, part of koffice.  samba's samba and you need that if you want to network with windows.
another nice lightweight is opera.  nice fast browser and elegant too.
pcliuxos minime 2008 is a stripped down edition for users to customise their installs.  it has the bare necessities to reach the kde desktop and is ideal for machines where you want to use lighter applications.  runs on rocket fuel and looks sleek.

Puppy Linux is a good option (it's my Linux of choice). It contains a broad set of everyday desktop computing applications. It won't look familiar like Ubuntu (or indeed pclinuxos) because it doesn't use the KDE desktop environment, but GUI is simple and clean and very lightweight.
The GIMP is always going to be processor and memory dependent because of the nature of the task (image manipulation), but the best advice is to try a few lightweight distros and take your choice. PCLOS, Puppy, DSL and Slax all come as bootable live-cds which don't compromise your existing installation.

I've run SLAX on a Pentium CPU (overclocked at 119MHz!!!)  with 76MB of RAM and a 100MB swap file.  It ran like a dog and opening more than two applications at a time caused rendering problems on the screen, but it was good for a laugh.  SLAX uses KDE which although lighter than GNOME it is still heavy on resources for older machines.  An Open/Blackbox WM would do a better job I'm sure, but never tried it.  MSWindows NT4 ran better (also slow) and I could even launch MSWord 2000 on it.  Running a 3rd party firewall, or AVG brought the little thing to its knees.

Yep that's a point well made. The big (pretty, whizzy) window app managers like Gnome and KDE exact a heavy price in terms of memory and processor usage, which tends to make the distros that use them less useful for low spec machines. Puppy uses JWM, which has a tiny footprint but is extremely quick; the downside of that is that it looks a bit Win98ish!
But if you are willing to "get your hands dirty" and experiment with Linux, there are some very good looking lightish ones available (iceWM and XFCE for instance)
One thing that does get often overlooked though is that memory is incredibly cheap these days, so if you have an old machine that can take another 256k or 512k, it's probably worth spending £20 at Crucial to upgrade it and reap the benefit in terms of performance. (and get a year or two extra work out of an old nag)

Quote from: axisofevil

I've got a 384 MB, 300Mhz PC for which I'm getting complaints about it being quite slow. It runs Open Office and Gnome (and Samba) (and a print server) on Ubuntu (latest upgrade). Gimp is, not surprisingly, quite slow. ... Any ideas?

It might be worth trying another window manager; Gnome can be a bit of a hog. Personally I use FluxBox, it's nice and light and fairly pretty too if you get the right skin for it.

Thanks for all the comments - I thought changing the window manager seemed the least invasive choice.
So I tried following some outdated(?) set-up instructions for fluxbox, which involved creating one file in my home directory.
When I tried a restart of X and gdm, I got a message saying that my "greeter application is crashing".
So I cleverly pressed the CTRL-ALT-F2 keys, to allow me into a command line to delete this file. Shock! Horror!
Looks like I need to try a small Linux such as Puppy or DSL or something. 
I'd prefer something that's Debian based.

Quote from: axisofevil

When I tried a restart of X and gdm, I got a message saying that my "greeter application is crashing".

Hmm, are you sure that you are not using kdm?  Try xdm as your login manager with Fluxbox as your window manager and see if you're getting the same error.

It was only a trial - on one of my better spec PC's.
I will try this on my slow PC - but in due course as my wife has a load of material which she needs access to for the next few weeks.
Meanwhile, I will burn a DVD for knoppix (just to try it) 

Hello!
I bought the WH Smith Ubuntu linux starter pack today (£9.99) because I'm fed up with Vista crashing all the time (screen freezes & does nothing - 9 times in one month!). I haven't installed it yet.
My system is - an Acer Aspire T671
Intel Pentium Dual core CPU 2.80GHz
2GB memory Ram
Nvidia GeForce 8600GT graphics (with 1791 mb total available gaming graphics) Direct  X 10.
and 250 GB hard drive.
it's running on Window Vista Home Premium 32 bit os.
I hope thats enough info for any help I ask for!!
I plan to buy a usb bus driven external hard drive to back up all my files - http://www.ebuyer.com/product/134379/show_product_reviews
Then I will totally annihilate vista (I won't dual boot) and use Linux only.
I gather from previous posts that as I'm using a wired ethernet router I shouldn't need any drivers? I should just be able to plug n play? (using safecom sammr 4114).
Also I have been using Norton antivirus - will I need to anymore? someone reccomended Avast anti virus.
I have been very happy and secure using Norton but am happy to change on reccomendation. Is an anti virus still needed?
My main use for my PC is internet browsing, forums (Facebook, Myspace, Youtube) etc... will all these be ok on linux - mozzilla etc..?
Also my other main use is Video editing. at the moment I've been practising on Windows movie maker - very basic and simple to use. Will I be able to play the files I've made so far?
What other free editing packages can I use that are comparable?
Can I open all the word docs I've made (CV's etc) on windows on an Linux word document maker thingy?
The Graphics card I bought (with the idea to stop Vista crashing!!) states its certified for windows vista. Does this mean it will only work for m$ vista?
other bits on the box - NVidia Geforce chipset. Complete direct X suppport. Full openGL 2 and lower support. I don't know what any of that means! But is it helpful to me if I change to Ubuntu Linux?
Thanks for any advice in advance. BTW I'm not a simpleton, but I like things simple! 
Matt

Sorry the other bit I meant to ask!
I use an Xbox 360 will that still be okay to use on my 4 port ethernet router (safecom sammr4114)
it won't get funny if my PC is on running on Linux?
Thanks again 

Everything is independent on a network!
So the Xbox will continue.
That external drive (with Formac Disk Mini hard drive - 250 GB) powered by the USB bus sounds a bit dodgy - but what do I know?
It says that it requires an OS of Apple MacOS X 10.x, Microsoft Windows 98SE/2000/ME/XP - which either means they haven't updated the description for Vista or it requires some special driver.
Most likely it will work if you have a FAT32 file system (Ubuntu supports this).
Nvidia (graphics and motherboard) is a good choice for Linux. Well it works for me.
You will get a decent graphics driver with Ubuntu.
If you are using Open Office (don't use AbiWord...) you can import all Word docs / Excel etc.
Not sure if it will convert the Office 2007 versions...
Firefox is excellent for all browsing & there are also plenty of chat apps you can use.
BTW Linux comes with quite a lot of games that can be installed...
You can play most of the various video formats you find on the web - don't know about your Windows ones.
Could you convert them to avi or mpeg4 or something similar?
I strongly suggest you look at an application called "Miro" - it provides thousands of channels of video,
set up like a downloadable internet application. Lots of educational channels.

Quote

Hello! I bought the WH Smith Ubuntu linux starter pack today (£9.99) because I'm fed up with Vista crashing all the time (screen freezes & does nothing - 9 times in one month!). I haven't installed it yet.

Sorry to disappoint you but Future Magazine are giving that pack away now, e-mail paul.hudson@futurenet.co.uk with your address and they will send it to you, offer was in PCplus and PCanswers current edition

Thanks for replies so far 
Does anyone know of a suitable video editing package that rivals / superceeds Windows moviemaker & is cost free?
@ Pierre - flaps! I only bought it today! nevermind 
Thanks again.  Matt

Never really tried Win MovieMaker
You could try VirtualDub in Windoze.
There's a small bucketload available under Linux -- LiVES, Kino, Cinelerra to name a few