Live One Care's part of Windows Live, it checks for visuses, spyware, reg problems, defrags, but you have to load it through Internet Explorer (doesn't support firefox), it's a free scan online. Don't click on free trial, just on scanner when you scroll down a bit. I just use it if I might have a registry issue or check for viruses every few months (AVG free usually finds those though). Needs to be installed every time you want to use it.