Actually, to my surpise I've managed to use print-screen to make a screenshot from Media Center. On XP it results in that weird black effect, but on Vista I actually managed to make a screen grab. I have no idea why it does work now.
How this makes one OS better than the other, or what this has to do with DRM, is a mystery, however.
Anyway, now if Windows 7 fixes print-screen to preserve the alpha channel when you take a shot of a single Window so that you don't ruin the glass effect, it'd be pretty much perfect.