Eric, did you actually READ the contents of that link???
Richard....my advice to you is to determine how much money you are truly willing to spend....and keep in mind that the same amount of money you spend now will likely be the price of a machine that's roughly 1.3 times better in 6 months (hint....take what you're willing to spend and multiply it by 1.3)....
and look for....
3 GB memory
a 7200 rpm drive
a nice Widescreen HD monitor
as someone else stated, a dual-core CPU
And then Visual Studio will hum...