Yeah really, I mean it's all up to you. Thats a nice cheap route to succeed in what you want.
Depends on your budget though. 790GX definately worth it.
As hikari said, you won't go wrong with the X3, the quad cores do some major multi-tasking though.
For instance on my setup, I run WoW, about 3-4 browsers with 6 tabs each, I fold my GPU and CPU, 4 different messengers, Anti-Virus blah blah blah. Lots more and never hit over 75% and still see 60fps. Though graphics card comes in to play on that as well so.