Have you seen the specs of the mac pros and servers? lol..
http://store.apple.com/us/browse/home/shop_mac/family/mac_pro
But at the end it would cost more, and I can't understand why anyone would what to run windows as the main os on a mac when they can build the same spec machine for cheaper.
Certain programs just runs faster on an OSx machine than windows of the same spec, but that's more program dependent to OS than hardware or manufacture of machine.
But they won't be cheaper. Mac pros are workstations not desktops... Go spec a similar workstation on the dell or HP sites and they will come out at a very similar price. I know, I've looked before..
