Today, I hit Upgrade in the Update Manager, and less than an hour later, while I continued to work, my work computer went up to the latest Ubuntu Long Term Support (LTS) version. I got asked one question (about overwriting a configuration file) then had to shut down all running applications while it did a 5 minutes cleanup. Then, it asked me to confirm reboot.
It came back up and ... no problems. Clean, fast, stable, kept all my settings, all my old stuff works.
Ubuntu is a marvelous package: Linux-based operating system, and a host of free programs that are capable and powerful. Recommended.
Incidentally, there's also a program called Wubi that installs Ubuntu on your Windows system -- you can try it that way, without compromising your Windows system at all. Link: