I might be a bit late in responding, but if you haven't bought yet, I'd recommend the eVGA 7600GT KO.
It has an extra large copper heatsink, compared to the nvidia reference design (the 7600GT CO).
You just install it in the PCI Express 16 slot. It does not require an external power hook up to the PSU, and the card's onboard fan is already plugged in to the card.
It runs very cool and quite. My GPU typically measures in the low 40's.
This is in an Antec 1050B case with a single rear 120 mm fan running on low, with ambient room temps of about 22C.
-Bob