Avoid at all costs
DO NOT BUY! When I first used system mechanic it was great it significantly speeded up my 18 month old PC. But after a couple of weeks of it "fixing" registry errors and problems with windows, it irreprably damaged windows, I couldn't connect to the internet, half my programs wouldn't run etc, etc... The end result was I had to remove windows and reinstall, only I couldn't even do that because it had messed up the partitioning of the hard drive. severals hours on the phone to the Dell help desk and an expensive call out later I'm back up and running but my PC's still not running 100% correct. DO NOT BUY! use the free one off down load to clear system clutter and optimise your internet connection if you must, but don't let it play around with windows, otherwise you may as well throw your PC out the window.