I tried Parallels as well, but I had all sorts of problems - I couldn't even get XP to install - it kept locking up at some late-ish point in the in the setup routine. So I put temporarily Win2K on the Parallels trial, then put MC12 on that. I saw (possibly) the same issues with Coherence that Glynor described. MC12 initially opened up fine in the Mac OS desktop, but if I attempted to move or resize MC12, I started to see issues. For example, if I dragged MC to the right, the right side started clipping off. Same thing with resizing. It was as though Parallels had created a 'viewport' positioned and sized where MC initially was, but it remained locked in place from there on.
I also tried the VMWare Fusion beta, which essentially does much the same thing as Parallels. It seemed to like XP more. Its 'Unity' mode (which is like Parallels 'Coherence' mode) works fine with MC12 - even with a 3rd party skin that makes it look more iTunes like. But it too can't use Theater View. VMWare has 'experimental' 3D support, but not for the Intel GMA 950 in my Mac Mini. It let me trying activating it, but suggested with the 950, it probably wouldn't work. I just got messages about not being able to start Direct3D - MC didn't crash or anything.
Hope this helps.
Just for fun, I fired up both virtualization systems, MC12 in each, plus iTunes in Mac OS. Then set all 3 media programs playing different tracks. I was rather amazed do find the Mac Mini took all this in stride (though the resulting cacophony did send my cats running for cover.../)
Stuart