I don't know if I would go with a 7750 with such a small PSU. I think you probably have the same PC as my brother and I was told that a 50w GPU is about the max that PSU can do, and I wouldn't even go that high. I actually threw a 5450 in his so he could play WoW with better fps (yes the 5450 is more powerful than the onboard), but you could probably go a little higher than that. I'm thinking a 6450 would be about as high as you should go, they pull about 35w I believe.