Re: Cpu upgrade
There is no processor for gaming for under $100.
You'd be better off upgrading that aging 8800GT, or a completely new build if you want a gaming machine.
I don't mean to sound rude, but trying to make a gaming machine out of your present computer is like trying to make a race car out of a 10 year old 4cyl. Nissan Altima, with 200,000 miles on it.
HAF 932 Advanced / Corsair AX1200 / Asus Rampage IV Extreme / i7-3930K / H100 Cooling 4x120mm
16GB Corsair DDR3 / GTX 580x2 SLI + GTX 460 PhysX / SSDs Mushkin 240GB, Crucial 256GB, Crucial 512GB