Having saved a bit more money than expected this month I'm contemplating buying a new computer. But I must admit I get easily confused with specs and am a bit worried about paying out for something which I could have got cheaper/better elsewhere.

If anyone is bored enough to try and make one for me here are the rules:
1. UK supplier please as I don't think delivery costs and import charges would be nice (not to mention me actually understanding them ).
2. I still don't have much money to spend, so I'd be looking at around £400-600 inc VAT and delivery.
3. Obviously for that price I'm not expecting top-of-the-line, I'd like something that beat my current set-up (shouldn't be hard):
Processor: AMD Athlon 64 3800+, MMX, 3D NOW, ~2.4GHz
Memory: 1022MB RAM
DirectX Version: DirectX 9.0c (4.09.000.0904)
Graphics Type: 256MB ATI Radeon X1300 PRO
Total Memory: 256MB
4. I'd like it to have a reasonable chance of lasting me a few years before becoming obsolete.
5. I don't need a monitor, but will need an operating system (pref windows), I have office at home so it's not an issue if it comes with the pile of crap which is Microsoft Works.

I've come up with a couple of comps myself, but the graphics seem a bit on the low side, problem is I don't really know what to expect at that sort of price range.
The one i was looking at is http://www.meshcomputers.com/Default...UCT&KEY=361215

Removing the monitor, but not adding to any of the options it ends up at £425 (can add £20 for a Nostromo N52), I have a feeling that the graphics could be better though, but wasn't sure if any of their upgrade options were worth getting.