There is another function of the default Disk Cleanup that can remove lots of unneeded junk, such as those massive collection of Windows Update installers. First, run the standard Disk Cleanup. There will be an option to "Cleanup System Files". That's the one that does the real cleaning.
But be careful when selecting to clean driver install packages, as while these may not be needed, it's possible that they may. This cleanup will take several minutes & a possible reboot to finish (reboot anyway). It may appear as though updates are configuring again, don't worry, they won't install again.
I gained nearly 2GB of space with this option on one computer.
Make duplicates of the folders that's used, such as Documents, Pictures, Downloads, etc on a partition of a Data HDD. This HDD doesn't necessarily have to be permanently (or internally) installed, it can be attached by USB docking station/enclosure. Store your downloads & other items of importance there & for extra protection, on another drive or CD/DVD, Flash drive, SkyDrive or Google Drive.
It's best, SSD or HDD, to store these items off the "C" drive anyway, in case of hardware failure or infection. The fact is, hardware fails & the HDD is a common item to drop first. While I backup 2x weekly, one automatically with the inbuilt Windows Backup, one with Macrium, I realize that many doesn't. Protect your data, OS's can be recovered, your data is priceless,
Cat