I think you mean this:
You want Halo Wars ported to PC, then you enter your Xbox Live credentials and you'll be away right?
Primary flaw with Halo Wars on the PC is that the control system will not be set up for PC, but that is an easy fix.
Another reason is that the game is a so called 'Xbox Exclusive', it will be on sold on the PC within two to three years I think. Remember Halo: Combat Evolved?
They just want to suck our money out of us through Xbox Marketplace, I mean its a bit more difficult to circumvent than pirating right?
I think this game is already on tpb anyway. And if you can't figure out what that is, you don't need to know.