I know some members use PSUs from Quiet PC & others but I'd suggest an Enermax. I have a 550w model & it is very, very quiet when the rear fan is at minimum speed. You may not need 550w but they also do 380/450w models.
You do need a bit of "oomph" with an nForce 2 mainboard.
Antec's 380w model is also very quiet (single 120mm fan IIRC) & worth considering.
Point of interest. A "cheapish" PSU went pop on me last year & killed 2x WD HDDs (Raid 0) as it went. Always worth spending a little extra for a good PSU.
I've been running that Antec Truepower in my new system for almost two weeks (included in the Antec Sonata case) - with an AthlonXP 2500+ and the A7N8X Deluxe (v2.0), by the way.
And... so far, no problems. Quiet, with very stable output and it's quiet. Er, did I mention it's quiet?
If it helps to give some idea of capability, I currently have a Pioneer DVD-R, 10 Gig IDE hard drive, 160 Gig SATA drive, Voodoo 2 video card, floppy drive and a Radeon 9000 Pro installed. Oh, and some new-ish Sennheiser HD-495 'try to kill everything they get near' headphones! I'm expecting to add a second IDE hard drive from my old system and perhaps, an old Toshiba DVD drive - with the possibility adding a PCI TV card soon. I think it'll cope... er, if I remove the 495's!
Oh, almost forgot! There's bits hanging off the motherboard's gameport and USB ports (including a hub, with more bits-a-hangin').