Past performance is no guarantee of future results. (High resale value is a big part of why Mac TCO may be lower, but the market 3-5 years from now is unknown).
You've already stated a preference for OS X so why are you still considering a PC? At this point in the Mac Pro and iMac lifecycle, I'd look for a good deal on a refurb from the Apple store or just wait until the next refresh.
B
AH i was just getting facts straight. I will wait for refresh.