You can use a duplicate finder like CloneSpy Sometimes you find quite a bit of space in duplicate files. If you have folders with lots of fairly compressible files, turning Windows native file compression for those may also save some space. From time to time, I search for files over 100MB or so and often find something I really don't need. Files I don't need often I compressed with WinRAR - which allows adding recovery records to the archives. Disk space may be 'cheap' but it ain't free :-)

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken