Backing up files

Making a big backup and cleaning up some old data on my PC, I realized I had accumulated about 6 GB of data inspite of (inconsistent effort I have to admit) to delete stuff that I thought was no longer needed. Most of the stuff, were pdfs and html files that I thought were interesting and downloaded to read later, but I never got around to reading most because they lost their interest at the time. Anyway I deleted about 2 gigs, and I still have about 4 gigs left, which I'm now transferring to another computer. I'm pretty sure there is plenty of junk in that 4 G that I probably should get rid off. In other news, I download the new iTunes software that supports pod-casts, and it deleted all my playlists. I'm kinda pissed right now.