The Risk:

On-line Computers can be very vulnerable.  If you have a computer connected to the Internet (dial-up, cable, DSL, satellite, etc.) you are at risk of having your computer taken over by criminals. Here's a look into that seamy world and how you can protect yourself.-- the risk is incredibly high. Researchers at the Internet Storm Center completed a study that found that an unpatched Windows PC connected to the Internet will last for only about 20 minutes before it's compromised by malware. That figure is down from around 40 minutes that the group found in 2003.

Don't Let your PC be a 'Bot! If your PC does not have a two-way firewall and antivirus protection, you could be an unwitting 'bot. It's more than just your PC slowing down. While the cybercriminal in this article didn't do more, there's a LOT more he could have done and they usually do.

Identity Theft.  A most likely possibility is that when criminals have taken over your PC, they install a keylogger that captures everything you do on your computer. The cybercriminal then retrieves the log and extracts all sorts of YOUR sensitive information (credit card numbers, Social Security numbers, birthdates, Mother's maiden names, etc.) and then uses it to either create credit cards in your identity and withdraw as much of your money out of your accounts as possible.