'C_C',
Ok, assuming there are 2 drives (partitions) available...
You install 1 OS to a drive.
You install 1 (2nd) OS to the other
When you boot there is a screen showing the 2 OSs
Select the 1 you want, @ that moment & carry on. So ye, as you say, just all by itself.
You can dual-boot XP/Win7 though, remember, you can, also, w/ Professional & Ultimate run XP Mode virtually on them. Or, you can install your own XP on Windows 7 Home Premium as a virtual machine.
Just some options...
Regards,
Drew