Based on the number of queries I've had from friends and family over the weekend, fake callers pretending to be from Microsoft and offering to help "fix" a security problem on your PC are once again active in Australia. If you get one of these calls, don't even waste time chatting to these charlatans: hang up as noisily as possible.
It shouldn't come as news to regular Lifehacker readers that these callers have nothing to do with Microsoft, and nothing to do with fixing your machine. Instead, the caller will try and guide gullible computer owners through the process of installing a so-called "patch" which will actually add evil malware apps to the machine, monitoring passwords, stealing information and making your PC part of a "botnet" used to distribute spam and other nasties.
If you act as regular tech support for a family member, it's worth mentioning this: a quick message now is much easier than hours spent trying to fix up a compromised machine. The bottom line? Microsoft is NEVER going to ring anyone to tell them they have a security problem, and nor is any security software vendor you can think of.