New system built

if you are concerned about power consumption, and still want high performance. look into nVidia's hybrid SLI. basicly if has low power onboard graphics, and then you add it a 9800gtx (only the newest GPUs work for it I guess) the IGP runs the web surfing and other normal stuff, and the discrete shuts itself down. when you fire up a game, the discrete fires back up and takes over. saves about 100 watts, pretty huge for a 24/7 computer.

I'm not sure how widespread the hardware has been launched, but I heard its availiable in europe.

you may also want to consider AMD/ATI, some of thier stuff is very low power.

if quiet is a huge concern, think about water cooling.

I don't know about the PSU and RAM you picked either way, but look for 80+ efficency in your PSU, and get one as small as possible. a 1000 watter pumping out 150 watts in idle isn't as effiecnient as a 400 watt PSU putting out he same 150 watts even if they are rated at the same efficiency.

I'd loow for low voltage memory. 1.8 volts would be great, 2.3 would not.

Its a bit funny, but the 1GB 8800GT is cheaper as the 512MB

Will got for the Seagate 7200.11 HD

About the nVidia's hybrid SLI, sounds intresting, have readed about it. But i can't find here. (in the Netherlands or Germany online sellers)