I saw this article the awhile back and thought it was pretty interesting.
Macworld | How Psystar’s computer measures up to a Mac
Basically it says "Psystar’s performance was somewhere between the Mac mini and the low end 20-inch, 2.4GHz core 2 Duo 20 iMac. Speedmark 5 results show the Psystar to be 28 percent faster than the high-end Mac mini and 8 percent slower than the low end iMac."
So for about $750 you can save some hassle of creating your own and get somewhere in between..... if they're still in business after the Apple suit