.
This is a common scam. Microsoft will
never call you, and have
no way of telling that you have a problem with your computer. These people want to gain remote access to your computer to root around for personal info (credit cards, banking details etc) or to leave you a nice little virus or trojan that will crate a back door on your syem and coujld allow it to be used as part of a botnet.
Just treat
ALL unexpected communications - via phone or e-mail - as a scam and you won't go far wrong. Don't open attachments, don't click on links in e-mails or on websites if you don't know where they are taking you and don't give people your email address unless you know them. Set up a 'junk' e-mail address for filling in forms etc online - eg a temporary hotmail address that you can dump later.
And - make sure you have a current, up to date antivirus programme on your computer.
Microsoft Security Essentials is free, effective and unobtrusive. If you regularly visit unknown websites then you might also want to download and install the paid for version of Malwarebytes Anti-malware (£20) - this can spot exploits that antivirus programmes miss.
People are welcome to PM me with any questions, or just post them here or in the
Bits and Bytes forum, which was created specifically for that purpose.
Stay safe.