You know, I'm wondering if you may be better off just changing platform altogether. AMD has some very affordable Athlon II platforms...
MSI 760GM-P23 - $54.99 Kingston 2x4GB 1600MHZ DDR3 RAM - $34.99 AMD Athlon II X4 640 Quad Core Processor - $69.99
Total: $159.97 + taxes/delivery.
You'd get a pretty major bump in performance over your old X2, and all for less money than you can spend on a new APU. You could then look for a used video card on the forums, or even go for:
ASUS Radeon HD7750 V2 - $112.99