If my MB has a built in 4550 GPU and I add an ATI 4650

Well personally I would get the best GPU that your PSU/budget can handle. I would go with 7750 GPU at the least (it doesn't require any extra power from your PSU - not PCI-e power connector needed, just the supported 75w from the motherboard PCI-e slot). The 7850 1 gb would be the next step up, but it all depends on your budget. Most onboard GPU's don't do well with dedicated GPU's (Xfire) from what I've read. Your better off with a decent dedicated GPU than trying to get a cheap/low end GPU to mate up with your onboard GPU.

This was put together with parts I had left over ,computer works so well decide to use for those 2 games .
psu is Antec hcg 620 so no problem for pci-e power ; OS is 7 pro 64 with only 8 gb of G skiill ram
So no way the 4650 + on board cuts it ?
What's the difference between the 7750 and 7850 is it a big step from 77 to 78 series ? AMD has the most confusing system where numerically higher is not always better would a 2gb card be better or is it a waste ?
Any brands of cards to avoid these days /
Thanks

I like the 7850 2 gb card over just about any other out there for the $. The 7870 is an upgrade from the 7850 and the 7950 is the sweet spot for performance/$ at it's price point. Depending on your budget I would look at 7750<7850 1gb<7850 2gb<7870<7950.

thanks I ll look for a deal on a 7850 2gb or 7870