BEWARE: April 2014: If you receive a call from Microsoft Support (usually an Indian accent) saying your computer has a lot of errors and they will fix it for you, this is a Scam to gain hidden access to your computer. Believe me I've seen it happen to a customer. It's particulary opportune for them at the moment because of the end of support deadline for WindowsXP on the 8th April 2014.
Don't do want they ask, if you have the time and want to have a little fun, play the role of a really dumb user. They will eventually hangup and not call again and the all will probably have cost them too.