Using XP, I have come into using most of System Mechanic 5 to maintain my system. As much as I know, I still don't feel comfortable when many duplicate files are found throughout my drives. I know SM5 will show a pop-up if a critical file is about to be disturbed or removed, but I would love to know whether the rest can go, or if there is anything to watch for. I am also aware that certain things should be left to experts, but i am getting there, and feel comfortable with most things. If it dies, I can always reload and restore, but I feel that learning through experience is priceless.....

If in doubt, ask! Any thoughts?

I would do a complete system back up (use Nortan Ghost or something) hmmmm best advice is to clean those file out by hand. I know it takes a long time but you get more of a feel for where they are and if they are needed. I would use system mechanic to find the files then clean them.