That is not a good game processor.
Xeons are not meant for games. They use a special error-corrected buffered RAM which has a much higher latency than ordinary memory. Because of the high-latency memory, the massive amount of cache offers nothing to improve game performance. There are no current games that can take advantage of 4 modern processors, and future games will be offloading so much general-purpose computation to the GPU that you will see no benefit later on either. That's also, specifically, a poor choice for a Xeon because it only supports a 1333 MHz bus - Xeons use quad-channeled memory, so I'd never ever get a Xeon slower than the 2.8 GHz Harpertown (1.6 GHz bus). And because they use quad-channeled memory you should also invest in two matched pairs which will probably bankrupt you.
Xeons are meant for audio/video encoding, servers, software development, 3D design and other tasks that benefit from a huge amount of cache and don't suffer from a high-memory latency. Tasks where buffered/error-corrected memory is a requirement and in the sort of situation where you'd want a Quadro for the mathematical accuracy even though the performance is terrible.
Basically what I'm saying is that, if you really want a quad core you should get the Core 2 Quad Q6700, which is $100 cheaper and 333 MHz faster than the Xeon you are looking at. But really you should get a Core 2 Duo. And since you aren't wasting so much money on FB-DIMMs and quad core you'll be able to splurge and get something ungodly fast and probably a water cooling system to go with it.