It all depends on the parts, are you planning on gaming, web-browsing or what are you doing with it? For $700-800 you can generally go somewhat mid end to high end. A prebuilt that price will get you NOWHERE near what you can build for a PC for the same price. Some prebuilts can be more expensive and still be trumped by computers that are custom that are much less for the price. Most gaming PCs are generally in the $700-$1000 line.