Booting Secondary Mac OS Drive as VM

I have two, internal, bootable hard drives in my Mac, one with OS 10.5 and the other with OS 10.6. Due to the version requirements of the software I am using on a daily basis, I sometimes need to boot into the other OS.

Currently, I have to restart the computer and select which drive to boot from, which is really annoying if I have to do it several times in a day. I would much rather boot into my main OS 10.5 and then boot my OS 10.6 drive as a Virtual Machine in a new window so that I do not have to restart the computer.

Is this possible with Parallels Desktop? If not, is there software that will allow me this capability?

Thanks.