To be fair, fans don't consume a hell of a lot of power. These are my machine specs (or at least the major ones):
Asus P4P800 Motherboard (which I'd recommend, it's an excellent mobo)
P4 3.00GHz (800MHz fsb model)
512Mb PC3200 RAM (go for the dual channel stuff, it's a lot faster)
120GB SATA drive (which I use for doze)
80GB ATA drive (which I use for linux)
Radeon 9800 Pro (which I use for some kickass graphics )
It's all in a very nice chieftec case with 4 silent case fans (2 intake, 2 exhaust), all running on a good quality (and that's important) 340W PSU that came with the case. All runs fine, no stability issues, and the CPU is at a more-or-less constant 25 degrees celcius, apart from when it gets really processor intensive.