Folding@home and BOINC can be run simultaneously, though I suspect that very few people actually do it. This can be done either by running multiple VMs or by simply running both clients in your native OS. The two will compete for hardware resources and the fundamental issue that has to be worked out is how your system will allocate those resources to each project.
Folding@home projects are on a strict deadline, and many projects earn more points when returned more quickly, so allocating less that 100% of your system to FAH will reduce the points that FAH earns. Using separate VMs doesn't change this fact. Some BOINC projects are also deadline-critical while for many BOINC projects, the deadline is more of a guideline. (You'll have to get that kind of information from BOINC.)
The BOINC + FAH question has been asked a number of times on this forum. You'll find additional information by searching for topics about BOINC.
ok, I found some BOINC threads. What i'll probably do is run Fah on a dedicated machine and run BOINC on my Win 7 machine. I'm more familiar with BOINC settings.