Its a bit of software that allows you to run multiple OS systems on one PC, say I could have XP installed, then run Vista (or linux) on a "Vritual Machine" using VM ware, the simulated machine will be slightly slower but the advantage is you can test it out without having to actually install the OS on a hardware computer, like dual booting the OS.

If that makes sense.

So in your case you could run linux, see if you like it, if you dont just delete the virtual machine, or if you do, get all the stuff you know your need, via running the virtual machine and then swap over properly. (or dual boot)