Agree with above post, you are def. in need of a new psu if its in the 400 range, and don't skimp on it either, you'll regret it down the road!
I recommend Corsair for their reliability and internal components (quality) they can be had for around a 100 for a decent one that will meet your...
TBH the 670 is the best card on the market at the moment for the price, the performance is amazing,
especially if your only running a single monitor or at least playing games in single monitor mode, not
Surround or eyefinity! Max Payne in 3D is still around 60fps!! Skyrim is around 100fps in...