stock 350w dell PSU
4GB @ 800MHz
Q6600 @ 2.4Ghz
stock dell mobo for inspiron 530 original case and dvd rom drive and HD
with 2 maxtor 500GB HD's(yes before they were bought by seagate)
stock intel heatsink
plus i us a Razer Megalodon on it
With that psu only the 7750 like this one : http://www.newegg.com/Product/Product.aspx?Item=N82E168...
It's the same price. And the reason is cause that psu doesn't have a pci-e 6 pin connector (100 % sure) and the 650 needs one, the 7750 doesn't need external power.
Not much of a loss of performance to be honest, the 7750 has the same performance as the 650 the only thing bad is the game offered.
Unless you want to cough up some dough and buy a new psu.