Good advice on the PSU above, Russian's system looks like a good way to go. There will always be faster memory for much more money like everything else...OCZ has dropped in price a lot lately, I am thinking of picking up their DDR 2GB kit. My advice to anyone esp overclocking/running high(er) end video...stretch the PSU budget has far as you can. I have swapped many PSU's in the past that resulted in machines going from flakey to ones I never hear about. Most of the time these did run fine stock, but once the person added another HD or upgraded the video card, etc they started having problems even though their PSU's were rated with enough watts.
Many PSU calcs error on the high side to factor in average PSU quality. Top tier PSU's can beat out overseas junk rated at 2x the watts.
I'd avoid Vista too. I work for a large Fortune 400 and Vista will not connect through citrix on our remote portals. Also I have had to get 3 associates now to go back to XP Pro/Home (I hate home but to some the cost difference was a factor) due to programs not working.
What's odd though is some of the problems (Slingbox esp) run on some Vista's ok, but others they didn't. These were both the same 'Premium' version...however the hardware was slightly different...both were Dell laptops though.