XP vs BenQ 955A 19" Display.

[#1]

You certainly got up to some archaeology for that info. Thanks.
I will explore Ebay to see what is on offer.

[#2]

http://www.ebay.co.uk/sch/i.html?_trksid=p5197.m570.l1313.TR0.TRC0&_nkw=Geforce+FX5500+PCI&_sacat=0&...
?

[#3]

Thanks Kelly,
I did have a trawl through ebay last night and found a variety of 5500 and 6200 video cards. I did not know that many manufacturers seem to make/or market these. A remarkable range of prices ranging from a few £ to nearly £100 are quoted. I have taken on board the special features to avoid like AGP, & PCIE from the posts above, but do not understand some of the others. Because I am limited by ancient machine with not a lot of spare space (230 mm length max and not much thickness for a fan) I need to refine what extras I should avoid. The specifications include DVI, TV (not needed), 3D, probably not required,  there may be others.
Assuming that I can lay my hands on a suitable card, what steps do I need to take to isolate the built-in video drivers etc. on the motherboard, assuming that all the connections will be made by the PCI connector?  

[#4]

It's pretty easy.  You'll get the card, slot it in, plug the monitor into the card and install the drivers.  Should just work.  Windows will then not worry about your onboard GFX.

[#5]

I've just had a look at the specification of the older Dell G110 (and GX110) - are you really running on an old Pentium III ?
You may find the drivers for a newer card specify a more powerful processor.
Personally I'd consider upgrading to a slightly newer machine. Pentium 4 machines (and above) are regularly given away free on Freegle/Freecycle.
If you're anywhere close to Wellingborough I'd be happy to keep an eye out for a machine for you.

[#6]

@ Kelly,
Thanks for that. I had browsed ebay the night before and was amazed at the variety of Nvidia 5500 & 6200 cards with similar, but not identical, specs that are available. I composed a reply to you yesterday but with one thing after another interfering I ran out of log-in time to post it. This often happens to me but I am loath to log-in with no limit unless it is vital. Has anyone thought of an early warning signal of time expiry in time to repeat logging in?
@ picbits,
Thanks to you for kind offer. I am in the wilds of West Wales and not able to do anything clever hereabouts. The old Dell was a gift from my son (ex-Reuters) when my older Win98SE tower went seriously belly up, leaving me without M$ facilities (my then laptop was fully Ubuntu). Since then the laptop also died a irreversible death and I have replaced it with a HP Pavillion with Win 7. You will see from my profile that I have plans to dual boot both machines once I have cleared up a few things with each. All this has been delayed by the monitor also going belly up, as well as a general lack of time to do much other than keeping more or less in control of things involving using both machines.
I had not heard of the source of elderly machines before, must Google them some time. Right now the Dell (which is  extremely well built) is a bit of a challenge as well as a reason for more education. Time will tell.