4670 isn't that much pricey. I don't know where'd you get that price.
You should definetly go with 4670. It is for 1680x1200
So you will get a great great performance at 1200x1024
Personally, I think you should consider 4650 too.
It costs less but plays every game at 1280x1024
I would say you go with 4670.
9500 GT is good but not as much as 4670