Hi Lyn - this is a known scam. Good job on picking it - if they call back again tell 'em to rack off.
The scam is that they tell you they are from Windows Technical Support and that you have critical errors/viruses/faults on your computer. They then offer to repair them - for a cost. Of course there is nothing wrong with your computer. Unfortunately many people have fallen for this scam. But not you!
Let this be a warning to others.

Have had three calls saying they are from Windows Technical Support. One guy told me his name was Leon Davis and that he was based in Melbourne, Victoria. When I asked for the physical address it took him a while before he came up with Kingsford Ave, postcode 3338. When I asked for a phone number that I could call back on he gave the the number above. His number had come up as Private on our caller id. He was quite persistent with saying it wasn't a scam but I didn't believe him.
I hung up and then a while later another guy rang also saying he was from the same place. I told him we were on the DNC register, asked him to remove our number from their database and that if they called again I would report them to the authorities so we will see if that has put them off or not.