I got an e-mail a few days ago from Comcast telling me I was most likely infected with a Bot. I didn't want to deall with them trying to help me remove it (and wasn't even confident that they could), so I used Acronis True Image to set my computer back to a disc image 45 days old hoping it wasn't installed by then.
I then installed a great free program called Bothunter that is incredible at detecting Bots (though not much help at removing them). Unfortunately within a half an hour it picked up signs of bot activity.
The only other image I had was 2.5 years ago, so I reverted to that date and had a lot of software to update or reinstall. It was worth it though, because Bothunter has now been running about 3 days and has not detected any Bot activity.
What a great program! If I get another Bot it will notify me almost immediately and all I will have to do is to save my data and to use Acronis to revert to an image that shouldn't be more than a week or so old (so no issues with a lot of software to reinstall).