If I'm working at home during the week, I get maybe two or three of these calls a day. It's a real pain.
When I occasionally have time on my hands, I try, through innocent queries, get them to claim they are from Microsoft rather than just "technical department of Windows". I'm sure their script specifically avoids such claims explicitly, but they usually fall for this when they try to ad lib. After that point I say that the call has been recorded and that they can expect to hear from my lawyers shortly. This usually results in some swearing on Mr Simon Watson's part, or a comical claim that I have been wasting their time.
Pointless I know, but a tiny bit satisfying.