You can make a so called ghost image of your drive (or partition for that matter) when you have a fresh install of windows and your basic apps and put that image on on another drive (or partition).
A ghost image is simply bit by bit what you have on a partition packed into a large file that can then be unpacked to a drive to make an exact replica without having to install everything. Then when you have loaded too much crap on your computer and want to revert to that fresh install, you simply copy the ghost back to the drive and you're back. You usually use it whe you're making several identical computers with the same setup (install on one computer, make the ghost image and unpack the image on all the other computerss - done) but you can also use it as a backup. You will of course loose any settings you've made after you made the ghost image but that's generally the idea with a reinstall...
Since I run dual boot, I always install the OSes, driver and apps that I really need and then make a ghost image of the C:. That saves me an evening of windows installations if I need to get a fresh start.
Again, no absolute need for a second drive. Cunning partitioning will get you a long way.