Scenario 2: Graphics Upgrade
Our second scenario is probably most interesting for gamers, given that a fast quad-core CPU from 2007 typically still delivers enough performance (especially if you've overclocked it). Experience shows that you should maximize graphics horsepower before going after more CPU cores. Our step from the GeForce 8800 GTS to AMD's Radeon HD 5870 provides a significant jump in both performance and visual quality. The latest cards support DirectX 11, while the GeForce 8-series tops out at DirectX 10.
The pricey MSI R5870 Lightning is similar to most Radeon HD 5870-based cards, but the product arrives overclocked to a 900 MHz GPU speed, and its beefed-up cooling solution allows the product to run at higher clock rates and lower noise levels than AMD's reference cooler. You'll have to decide whether or not that last few extra percent in performance and the noise reduction are worth MSI's significant price premium.