However, once Steam on Linux comes out I'd be happy to switch completely from Windows to Linux. But in the mean time, I have to stay with Windows.
Steam for Linux is out (albeit in beta), the problem is that it needs more games =P (although seems to be getting games at a faster pace than its Mac counterpart)
As for the actual topic: yeah, you won't get what you want with a virtual machine, the most you can get is VMWare and OpenGL 2 if I recall correctly (short of using a software renderer, which is what Mesa would do). Either dual boot or get a second computer and install Linux on it (in the latter case you could try to connect the computers so that somehow they can share the files without much problem, which would be probably much faster for debugging than dual boot - no idea what options are out there though).
Don't pay much attention to "the hedgehog" in my nick, it's just because "Sik" was already taken =/ By the way, Sik is pronounced like seek, not like sick.