don't answer the phone; they're scammers representing window and they'll suggest your computer is running slow.  They'll eventually try to get you to pay (charge card) to extend protection.  In my case they offered 1 yr ($112), 3 yr($312) or life time ($386)coverage.  Also when it came to charge card time, they have a "registration code" in the place of how much to be charged (ie., 5754.37).  Ouch! 5700 bucks.

the company is in india at kolkata at saltlake sec 1 owner rajes giri  s/o k b giri  company dose scam . they charges money from geuien person of aus ,cad ,swiss its a cal center tech process if anyone calls u saying i m caling u form windows do not belive them ............
                                                                                  your faithful
                                                                             tapan biswas an (a t l) of swap pc care
                                                               please ,please do not invast your hard earn moneyin this scam....................................................................................

I got the same call and he was actually rude to me on the phone with the indian accent and said that my computer is infected and to go to www.supportme.com.....hmmm?

This is a totaly scam, what they will do is try to get you to go to a website, and download a program  that will allow them access to your computer. once they have access they will hang up and download any files they find interesting ie they are looking for banking information credit statements etc. anything with which to steal your ID.
They go by various names, the one that called me said he was from the world security office (yeah right)
other names they go by are microsoft security team, windows security, AVG security, Norton Security, etc.

They have been very active calling Canadian numbers lin the past couple of weeks, I work in a call center for an ISP and I am getting 4 or 5 people a day calling to ask me about this.

my advise is to just hang up, then report the number to your local law enforcement agency .

just got the same call as others,told him,when my computer warms up,I'd call him back if he gave me his number,and, he did ! (fool),,,said his name was "paul brown",,,really poor english,,was trying to tell me my equipment was infected and he would run me through the steps to clean it up,,I don't think I'll be calling,...."maybe everybody should get together and call the [***] out of him",,,hope this helps someone to be careful,and remember "windows will not be phoning you"...see ya !