This ISN'T a memory issue at all, but one of hard drive space.

Time for a clean up.
I'd use CCleaner for starters and remove all of the junk files from your system. Then have a look at your installed programs and uninstall any you no longer use.

Once this is done, it's time to archive your data.
Music and pictures take up a lot of room, so best to burn them to CD for storage.