I just got a macbook pro and it came with Lion preinstalled, as well as a voucher for Mountain Lion! I've done some research on apps and compatability with Mountain Lion, and unfortunately there are discontinued apps I use that will not run properly on Mountain Lion. So I'm wondering if its possible to setup a "dual boot" on my 500GB laptop drive to run BOTH Lion & Mountain Lion? Are there any guides out there to achieve this goal? Any potential problems having two OS's on a single drive? For example, how would time machine work? Also, is it possible to do this without having to re-install everything? Is sharing data between the two systems ok, assuming this is possible at all? Thanks in advance for the help and reply. Its much appreciated.