so, the base system you need for 10.7 to upgrade would be 10.6.8. Do you run the whole thing on an Apple laptop?
One of the usual ways of running Windows and OS X together would be Boot Camp
, you can either install it on an existing Windows system or on the OS X. But for some stupid reason it requires that there's only one partition when you do this on OS X.
The downside of this is that you can't choose to install Linux.
Another thing is to get Parallels
(using this at work to run Windows programs) which is pretty nice, especially with the Coherence mode
Also found this nice How-To using VirtualBox