Randy,
use
PassMark Software - CPU Benchmark Charts to help you understand the different processors and video cards. Also, the speed of your memory will have a direct effect on the speed of you system. 2 processors may have similar names, but they may be vastly different in capability. i7 800's vs, i7 900's are a good example.
All of the machines I'm building I use 1600 and higher for memory speed. If they are using DD2 memory, they are old machines. Only get a machine with DDR3. No less than 4GB of memory. I wouldn't take less than 1333 unless it is a SMOKING deal.
Make sure that the hard drives are 6GB/s and that the MB can handle 6 GB/s.
Make sure that the LAN speed is 1GB/s, as this is the new standard.
x64 operating system (Win 7 Home x64 is just fine!).
If you go Intel, get a quad core or at least and i5.