Well, this question really depends upon what you'd like to do with the computer. If you like gaming, go with the PC, since you can easily upgrade when needed. If you want to do artsy things, like music/video production and editing, or photo editing, then go with the Mac.
I, personally, use my Mac for both; running BootCamp with Windows 7 to play games, and Mac for Logic Pro, Final Cut Pro, Photoshop, and the like. Depending on how you set up the Mac, you could easily get some great gaming performance out of it.
My schema, experience with both Macs and PCs.