The heat vs performance on the cpu and GPU would depend on die sizes, as 55nm use less energy than 65nm and thus produces less heat with the same performance. So with that budget you should be able to get a decent i7 build, maybe a GTX 285 which produces less heat than the 280 due to smaller die size.
COOLER NorthQ Siberian Tiger NQ-3580
CASE Cooler Master Sniper
POWER Cooler Master Silent Pro 500W
MOTHER Asus P5QL PRO Intel P43 LGA775 ATX
CPU Intel Core 2 Duo E8500 3.16GHz 6MB, 45nm
RAM Corsair XMS2 DHX TwinX 4GB (2X2GB) PC2-6400 DDR2
VIDEO Gigabyte Radeon HD4850 GV-R485MC-1GI
HD Western Digital Caviar Black 500GB S-ATA 3.0 GB/s 32MB 3.5"
OPTIC Sony NEC Optiarc AD-5200S DVD-RW -tallennin SATA
OS Microsoft Windows XP Pro x64 OEM
So this is DRAFT 1 that I am thinking about. I do not even know if all parts are compatible. I imagine that all are high quality products, and will be a nice upgrade from my old system (GF 6700GT/AMD Athlon 65 3000+)
The blueray is +100€ so that is to much, I would probobly not use blueray so much any ways. Maybe I buy the "kids" PS3 in stead
This is now around 1000€.
What I want is a nice and quiet PC that can run games nicely also.
An energy efficient gaming rig is probably going to be a C2D . Lets pick an e8400 .
Its a 45 nm chip and draws 40 watts or so .
Gfx is going to be the problem . A gaming gpu uses more power than a cpu . Much more .
So if you hate noise ... put your computer in another room and have a usb connections to your keyboard/mouse and an external dvd drive on your desk , and get a dvi cable long enough to reach your monitor