As far as getting a GTX 670, not yet.
-You should take any money that you saved for the 670 and upgrade to a newer platform, youl get much better fps on every game doing that. Ill recomend a new Motherboard and Processor, which you can get both at less the cost of a new 670.
The price of the 670 is too high!
-Wait about 6 months when your Pc should be up to par with the 670, itl be atleast 50$ less by that point, the card just came out!
Need a quality PSU for your gtx 460?
-I know Psu's in the 80 dollar range still seem expensive, but the Psu is the foundation of any computer! 80-100$ Corsair PSU's will last a vary long time, and are energy efficient.