Need Investigation Help

I have a computer with winMe that I borrowed to someone. I found one file left in the outbox that leads me to believe this person was into some bad things. I have looked in windows files and all over but nothing else was left behind. I cannot restore to an earlier time either. Is there a way to check somewhere else for other web content they were involved in on my computer?

(nothing in history, offline web content, or any other windows folders)