"I want to reinstall the operating system on a single partition hard drive? Do I need to move all my media files to an external hard drive to do a fresh install. Thanks!"
I use the same partitioning scheme on my own Macs.
I find that by keeping the System files, applications and a slimmed-down home folder on a separate, smaller-sized partition, the computer runs faster and that the smaller partition is easier to keep backed up.
I then segregate data into other partitions based upon its importance. Again, this makes it easy to backup the important things, while leaving other stuff I consider to be non-important on a partition that doesn't get backed up.
If you want, you can also create a "second boot partition" of small size (under 20gig will do), and install a clean copy of the OS to it, along with a few utilities. If you do this, you can "switch boot" off the single drive -- great for if the main boot partition has a problem.