PSU Buying Advice

Can someone recommend a new PSU for me?

I've been using my current PSU for about a year (its unbranded and came with the case). Recently I upgraded to a Geforce 6800GT, Athlon 3500+ Venice, ASUS mobo. I've also got hooked up a CD Drive, DVD Drive, 1 HDD and two case fans.

All has run ok until I played Guild Wars when it keeps on crashing. It seems like its my PSU not being powerful enough.

Its 400w but the 12+ rating is only about 10 and a couple of people have said that this must be the problem- it should be at least a rating of 20. Can anyone recommend a good pwer supply for my system? I don't really want to spend more than £40-50 quid if poss.

Thanks All

I've got a Antec Neopower 480W which i really like. Has loads of good reviews. 12cm temp controlled fan which is pretty silent, braided, modular cables so you only install the cables you need, comes with sata, pci-express and 24 pin connectors. One feature i like but haven't actually had a need for is they provide 2 extra molex and sata connectors which you can add onto the existing cables if you need an extra plug somewhere.