Wireless network and JPGs

[#1]

I have 3 desktop PCs throughout the house and a laptop, all of which have to connect wirelessly to the router, because of the location of the BT socket. One PC runs XP, the others Vista. There is also a Western Digital NAS drive connected directly to the router. This holds MP3s and JPGs so that they can be accessed from any PC.
The MP3s work successfully using iTunes, but each of the JPGs takes anything up to 16 seconds to load (they are around 6MB each), whether using Windows Photo Gallery or Picasa. With the laptop connected via an ethernet cable to the router, loading each JPG is instantaneous.
I realise that wireless is not going to be as fast as Ethernet, but surely there shouldn’t be that much difference. My router is a D-Link DSL-604T, but I can’t see anything wrong with the settings. The wireless cards in the PCs are all TPLink 108m PCI cards. I presume I am running 802.11g.

[#2]

You need to look at the signal strength,
As the signal strength reduces so does the speed of transfer

[#3]

Two of the PCs show as "Excellent", the other shows as "Good". They all have the same problem.

[#4]

How long does it take to copy the image from the NAS to a PC?
Throughput is going to be at best 20Mb per second so that should be around 2.5 seconds to copy.

[#5]

I've just carried out a series of tests using a group of 10 .jpg files (total 76.5MB). The time taken was between 3 mins 10 secs and 3 mins 19 secs. So at best it was 19 seconds per file. There were no other applications running at the time, other than the copy.

[#6]

Quote from: waldron

I have 3 desktop PCs throughout the house and a laptop, all of which have to connect wirelessly to the router, because of the location of the BT socket. One PC runs XP, the others Vista. There is also a Western Digital NAS drive connected directly to the router. This holds MP3s and JPGs so that they can be accessed from any PC.

I have pretty much the same wireless setup (different OS, software). I use my NAS for backup purposes - it seems to "achieve" around 1MByte/sec in streaming backup mode.
Normally I'm using NFS on Linux - but the speed isn't much slower on a Windows laptop using SMB share-type protocol.
The problem is that a 54Mbit wireless can only achieve a maximum of 27Mbit in either direction - but not both directions simultaneously.
Knock of a bit for protocol overhead.
If your SAN sends a small chunk, waits for an acknowledgement before proceeding etc  you will see this really poor performance.
If you think this is slow, try a wifi PC-PC connection - it could take hours!

[#7]

So it seems that I am unlikely to get any better speeds given the current set-up. I'll have to consider alternative solutions - if there are any.
Thanks for the advice guys.

[#8]

Do you have enough spare room on each of the PC's to hold a copy of the JPG's? If you do I suggest you hold the master copies where they are now and use the Microsoft utility SyncToy to keep a copy in a local directory. You would run it on each of the PC's and it will update the local copy with all additions, changes and deletions.

[#9]

Thanks - that sounds like a possible solution. I have plenty of disk space available on one PC. I'll have to check the others. At first glance it looks like a nice simple way round the problem. It will save me keeping a backup separately as well. I'll check it out in detail after Christmas.