Processors: Athlon X2 4200+ - A beefy dual core chip for just £250.
Motherboards: Abit Fatal1ty AN8-SLI - An expensive but utterly top notch board. £125 including VAT, but worth it for a high end system.
Gigabyte GA-K8N-SLI - A socket 939 nForce SLI board with PCI Express, 3GB SATA, etc. and all for under £60.
I also suggest a "Coolers" section under which the Zalman CNPS9500 has to go. I've had mine for a month and it's amazing. Virtually silent and barely even lukewarm to touch. And that's with an overclocked CPU as well.
AGP Graphics card Geforce 7800GS http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=338481
PCI-Express G/C Geforce 7800 GT
http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=250971
The 7800Gt in particular is excellent value for money shame it's only for those with PCI-e
There are some very good PC games out there, Civ IV, AOE III, NFSMW, COD2 Quake 4 but nothing coming up in the near future that I'm all excited about at the moment.
I was looking at the XBox 360 and nothing on that really looks inspiring either. The last game I got really really excited about was GT4 on the PS2, but I've finished that and it looks unpolished and a bit shit compared to modern PC graphics.
Maybe the PS3 will bring with it a new Gran Turismo game that will get me into gaming again!