Local Drive Q

I was puzzled to find a mysterious local drive Q on my laptop and immediately jumped to all the worst conclusions; virus, root kit, daughter loaded some rouge peer to peer. It turns out it was just Microsoft again. I recently tried out the Office 2010 beta and it uses "click to run" which apparently uses their virtualization. See the details here . But the telling sentence is "Click-to-Run users may notice that they have a virtual Q: drive on their PCs, this is the virtual file system used by Office". Well, that's well and good but it doesn't look like a virtual drive although I'm not exactly sure what one would look like. I do know that I have less space on my "C" drive than I had before I noticed it but it says it has zero space allocated. I'll have to look more at it later just to know more about it but for now just know that it's not malicious.