I think programs like this target the Windows-to-Mac switcher simply because they're used to NEEDING to run this kind of stuff on a daily basis. Windows with its constant registry issues, leftovers in 20 different places (files and registry) and temp files where "temp" means "keep it until the drive fills up and even then, only remove it if the user specifically deletes it." With that said, I have also recommended this program to others. When you find a friend/co-worker with a 5-year old machine that's sluggish and out of space and you simply don't want to be the one combing through all their files deleting remnants of half-a-decade of deletions, it does do what it claims. It just doesn't need to be run weekly. For those asking about what it corrupts: I know that earlier versions had issues with programs (I believe Adobe) where thinning the apps of foreign language or code that runs on other processors would make those apps either stop working or refuse to be upgraded (failed checksums) but I have no experience with recent issues like that.