Uh...Windoze in Space?

I’ve been watching a lot of NASA TV lately (always do when the Shuttle visits the ISS, although probably more this time than previously).
One thing I’ve noticed a lot more this trip than any other: lots of stupid issues with Microsoft Windoze software. Problems getting email, problems getting printers to print, etc.
Now, I’ve seen lots of Macs in use at NASA. You can see them in Mission Control on NASA TV. You can see them in photos of the various labs all over the country.
Why aren’t they using Macs in orbit? I know Macs have their share of problems, too, but seriously. Email, word documents, printing…this kind of stuff works much, much better on a Mac than it does on Windows (if you don’t think so, you’re a fucking moron and should be sterilized to keep you from reproducing). Plus, you get the benefits of a virus-free OS. I know if I were in space, that’s what I’d want.