For example, use Mozilla for browsing
I've got a bit of a horror story about IE5. It was running on Win ME, and I'd noticed that the hard drive was very full, and that there was something huge in the Windows directory. I eventually traced it to Temporary Internet Files, but after "clearing" it, the directory was "empty", but still tool up loads of space.
Eventually, I found an article about how M$ can make files really hidden (not just hidden). I had to go to a DOS prompt and follow through some really complex instructions to wipe of a huge amount of stuff that had been left on. There was also a text file, containing every web page i'd ever been on.
That's why I don't use IE!