First off, it would be a better choice to pick a motherboard that nativly supports the AMD X2 series without the need to flash the BIOS (if they even have a new BIOS that supports X2), i would look for a new mobo.
That video card looks good, but you can get a 7800GT for under $300.
I would go with this power supply:
http://www.newegg.com/Product/Produc...82E16817103931, the one you picked out is good, but this has more amps, more watts, and is a better brand.