Since I cannot get my VisionTek x1550 series working on my 10.5.4 Kalyway install, I have decided to buy a new video card for the sake of CI/QE/Resolution, etc. My choices are :

ATi: HD 3650/3850
Nvidia: 7600GS

Please recommend a video card according to my hardware.

Mobo: Gigabyte nForce 3 250GB Series
CPU: AMD Athlon 64 3200+ 2.0ghz
RAM: 2 GB Corsair
PSU: ThermalTake 430w.

And that should be all the info you need to decide on a video card.
I, myself, is leaning toward the 3650, since I have heard you need a dual core to take advantage of the 3850. I would have to spend about an extra ~$100 for a Dual Core 939 pin on eBay for one.