Best video card for M3A79-T deluxe

You can put any GPU on the market in that motherboard depending on your power supply. How much are you looking to spend?

my system is actually is this one...

MoBo: Asus M3A79-T DELUXE
BIOS: 0703
CPU : AMD Athlon X2 7750 Black Edition
Mem : Corsair Dual Channel TWINX 4096MB PC6400 DDR2 800MHz Memory (2 x 2048MB)
Vid : XFX GeForce 9800 GT - 512MB GDDR3, PCI Express 2.0
HD : Hitachi Deskstar P7K500 500GB Hard Drive - 7200, 16MB, SATA-300
PSU : Ultra LSP750 750-Watt Power Supply - ATX, SATA-Ready, SLI-Ready, 135mm Fan
Case: Foxconn TLA776

but as I'm havin weird problems (image is always blurred) with the video card I've been planning to change it. I could spend around $100