I've been surfing the forums/reviews and have found ALOT of great info. here. I'm looking to upgrade my PSU and GPU after discovering the POS video card that came with my comp. won't run Diablo3. This GPU will be used to play D3 and World of Warcraft. Here is my current setup:
Compaq Presario CQ5320Y
AMD Athalon II x2 240 dual core 2.8GHz
Based on my budget(low) and info. I've gathered around this site I've come up with:
the best is getting 6670 and a 450W PSU (and the PSU you mentioned) imo will be enough, a simple OC to the CPU to 3GHz and you can play Diablo 3 all maxout with 40~35 fps avg, as for WoW medium settings will do fine in raids.
cx 430 will run a 6670. 6670 is a decent budget choice for diablo 3.
imo good choice on the psu.
make sure the card dimensions fit your case.
@RyQril: OP's prebuilt pc is highly unlikely to allow any cpu overclocking.