The gang at HotHardware has posted a Holiday Buying Guide for your viewing pleasure.  Of course, you can view our Hardware Leaderboard as well. 
Before we begin, it makes sense to outline our approach and illustrate what we’re trying to accomplish. It is critical to have reasonable expectations here, as no $1,000 system is going to compete with a $4,000 SLI monster. However, as you will see a budget system does not necessarily mean lackluster performance. In fact, every system we reference in this article would be more than capable of playing any game or running virtually any business/professional application on the market with very fluid performance, at respectable settings