it seems like it's a lot of work to save $10. if you're not ready to move to Win8, just buy the license and stick with WinXP. no need to go to all this trouble to just let the installation sit in a disk image.
but the sooner you start learning the new OS, the better you're going to get familiar with it. Like with Windows 7, the people that had Windows Vista knew all the "new" techniques of Windows 7 because Windows 7 feels very much like Windows Vista in terms of user interface. Same start menu, same shortcuts, etc. Windows 7 is just a tuned-up extension of Vista. But the people that jumped from XP to Windows 7, they had to make a lot of adjustments. And I know a ton of people that manipulated Win7 to look and feel like XP to meet their comfort level.
especially since Win8 is the new paradigm going forward for Microsoft. its design is pretty much here to stay. but worst case, there are lots of ways to make Win8 look and feel like Win7 or heck, even XP.