The only thing you might consider is when you are going to buy this system. The GFX card market moves so quickly that the best bang for your buck changes as new cards come out and old cards go down in price, so waiting as long as possible before buying and also when you do buy looking at whats available again and at what price is very worthwhile.
PSU: Coolermaster Silent Pro Modular 700w HDD: Western Digital 500gb Caviar Green 16mb CachePrice of build including Windows 7 Home Premium: £596.82I don't really want to go over £600 but if anyone has and suggestions/improvements then fire away.
buy a cheaper case and get a gtx460
SSD's are pointless at the moment, until they can get the price down then there really is no use in going for them over a HDD