The balance between GPU and CPU performance isn’t all that matters to World of Warcraft. Memory size is also a very important factor in building a smooth running WoW box. As with any high end gaming box, less than 512MB of memory is simply unacceptable for WoW. However, the requirements here are a little more strenuous than usual. We found that ideally, you need 1GB of memory to have WoW running on a machine that has other applications running in the background. While you can get by with less than that, for the best overall performance, the sweet spot is 1GB. With memory prices at the lowest that they will be for the next few months, making that 1GB or more upgrade is a bit easier now than it was before or than it will be later on.
World of Warcraft Performance Guide
If you have been playing or thinking of playing World of Warcraft, otherwise known as WoW, then you’ll want to read what Anand has put together as a performance guide. He has looked at both GPU and CPU performance in the game.