Dark Power PRO 450W (Might be in German, but just click on the UK flag and then on Dark Power PRO)
If there's one thing I won't save my money on, it would be the PSU. It's better to spend a few more bucks on a good one, than to get a cheaper one which could explode within half a year. I speak from personal experience, trust me. Well, not ME personally, but it happened to a buddy of mine. One day we noticed some weird smell, and when he opened his case, the PSU was already smoking and when he opened it, the transistors (or whatever is inside) were already throwing bubbles! A bit longer, and they would have blown up.
The 8600 GT is probably enough for your needs, but you have to keep in mind that Nvidia no longer builds cards of the 8 series. What is sold now is the rest of the stocks. For SLI you need two identical Nvidia cards, so if you decide to get a second one later on, you might have trouble actually finding one. That's why I suggested the 9600 GT. Yeah, it's a bit more expensive, but at least it will still be available in a year or so, unlike the 8600 GT. ![]()
And then I'd also suggest a better PSU, maybe a 550W one...