GeForce 450 is mid-range in its series, which wasn't bad at all three years ago when it was launched. An APU may include more modern technology, but it will still use regular RAM instead of GDDR3 or even 5 depending on model.
Run a test with both, since you don't have to buy anything for doing it. Play AH online with lots of eye candy on a freshly changed map for half an hour, then swap the graphics and try to use the same fields for another stint.