The upgrade includes a GeForce 8800 GT, AMD Athlon X2 4000+ processor, a new motherboard and 2GB PC2-6400 memory from OCZ. They assume you already have a case, HDD, operating system and some other components. If you're starting from scratch you'll probably have to spend about $700-$800.
There’s a silly misconception out there that you need to spend $1,500 or more to own a decent gaming rig. This is just nonsense, especially if you know how to build your own computer. If you know the right components to focus on, and pick them wisely, you can get by spending half as much as $1,500, if not more. In this article we’re going to make an argument that $500 is all you need. That’s just $50 more than an Xbox 360 Elite, and the same price as an 80GB Playstation 3. With this $500 investment, you’ll have a PC system capable of dishing out graphics that are better than either game console.Check it out over here. The article pretty much proofs that PC gaming doesn't have to be expensive.