Okay, well I know a bit about both powersupplies and video cards.
I'd say with an agp system, the best card to get for the money would be the 6600GT. And evga is one of the best (if not THE best) video card distributers out there.
eVGA 6600GT AGP 4x/8x for 139$, 119$ after rebates
And seriously man.. you don't need to spend 150$ for a good powersupply. With your system, these would run it with absolutely no problems.
Fortron Source 450W (18a on each 12v rail; 36a all together)
Antec Truepower 430W (17a on each 12v rail; 34a all together)
Remember you don't NEED to dishout 150$ on a good powersupply unless you decide to upgrade to a 7800gtx, an fx-55, or decide to overclock like crazy. Even then, a 100$ powersupply would suffice.