Another call today from a company claiming to be Microsoft representatives, kindly offering to fix my computer!
Microsoft NEVER call out, this is simply a scam. They will tell you that your PC has reported errors, there is a refund on MS Office or get you to enter some key commands that produce known output which they will tell you in advance. This is supposed to give them credibility.
The bottom line is they are simply after your money. Hang up.
If you have the time and inclination and want to string them along, say that yes, you are interested but just want to make a cup of tea. Play this Youtube clip to them http://www.youtube.com/watch?v=8-yU5Ekv14U
Drink your tea and enjoy!