Windows 8 Upgrade/Clean Install/New Partition Dilemma

So I have Windows 7 and use it as my main OS. It has all my files etc, and is great. Because I'm a student, my University gives free Windows 8 OS's so I now have Windows 8 too. I have one of the Windows 8 public betas on a separate partition.

I was wondering if I should:

1. Upgrade my main Windows 7 to Windows 8 (don't lose any files, settings, but there is a Windows.Old folder)
2. Do clean installation of Windows 8 on my other partition to test it out (it's a smaller partition)
3. Do clean installation of Windows 8 on my current Windows 7 partition (after backing up a shit load of files)
4. Do not install Windows 8 at all

One of the reasons I want to stay away from upgrading is because I've read that there is a Windows.Old folder that keeps all your old files/programs and I'm not sure if I really want that. I prefer a clean OS where I know where all my files are.