I don't think that hardware virtualization has reached a point yet to allow real-time audio in a virtual machine (Guest OS).
I totally agree.. I can't even get regular audio through my sound card to work correctly in a virtual, at least with virtualbox. It plays, then starts distorting and gets really bad, then clears up, then back to distorted. It's unusable. I don't think it has to do with hardware performance as much as it has to do with the virtualbox software.
I've surfed around on their forums a few times to see if anyone else has this problem and/or if there are any solutions and I see nothing. I've tried multiple different configurations, I either get no audio at all or the alternating clear/distorted sound.
I'm sure it would be better if I had full vmware or something but I'm not betting I could have a fully functional DAW.
But, if it would work, I would be all for it!!
PS - Another thing that is incredible to use are the portable apps.. portableapps.com. They are awesome!! Lots of windows apps for everything from office to picture editing to email and browsers. They all run from a directory, even on a thumb drive with no installation, no entries in the registry, nothing. Perfect for keeping a DAW pristine, and backing any of them up is just a matter of copying the directory somewhere else. They are all self contained! It's easily on my top 5 list of coolest things!!