I use the norton windoctor. Have had it for about 3 years and they haven't changed it since I have got it. Always find lots of problems after a fresh install. I can't say I know if I have had any registry related problems, but I run it pretty regularly after installs and uninstalls. It comes with norton systemworks. You can pick up the oem version for under $20 at newegg for 2002. The newest version has a bunch of junk with it now, and gave me some problems with sp2.