@Truth_and_Freedom Just as @jaytkay said.
Imaging you have a cluttered room, there is no space that you cans ee to put stuff. Defragging is like cleaning, there is the same amount of stuff, but it makes it easier to find a place to put it, and organizes the different things into areas.
Reformatting will completely wipe your hard drive, windows wont even be on it.
There are a couple things you can do, sign up at 4shared.com with a payed account, and you can upload files to their servers, then delete them off your computer, that will clear out the space, and you can download them later when you need them.
You can also go out and buy a 46 gigabyte flash drive, and copy as much stuff over to it as you can, then delete that stuff off of your hard drive. You can also do this is an external drive as I said before.
Yes, 12 gigs is a fair amount of space. Really, when your hard drive shows 20 gigs or less of space, you should get a bigger hard drive, or move stuff over. I currently have 85 gigs of free space on my HD, and it has never been below 20 gigs for more than a day.
You can get a 1 terabyte external drive for a little over 100 dollars, and is a good investment.
However, until then, since you can’t download anything, just watch it online with netfix, or go to http://www.letmewatchthis.ch/, it’s a great site that has pretty much every movie available for download, or watching it online.