Registry cleaners are "safe", but it never hurts to have a program make a backup first. Sometimes those programs can get a little overzealous and wipe out entries needed by some program to run.
As to the benefit you might get... I'd say minimal to none. Things have to have gotten pretty unruly for such a program to deliver a noticable change, and if things are that bad, you'd probably be better off just formatting and starting fresh.
I have a compaq Presario, windows xp-home, version 5.1, service pack 2 build 2600.I am wondering if I should get a register cleaner installed. I am not having any problems right now and wonder if I would get any benefit from such a cleaner Thank You, Northwayice