[Piwoslaw]

Here is a trick I learned from my Mom, and I use it under both Linux and Windows:
Make one account called 'Admin' or 'Root', and then an account for each user. The main account should have all the privileges, while the users' accounts should have as little as possible. ALWAYS log onto your user account, use it for browsing or any other work. NEVER use the main account, except for updating, installing, etc., after which you immediately log out of it. If you use only the user account without privieges, then it is much harder for malicious software or hackers to do anything to your computer.

Also, DO NOT leave your computer on if you are not using it. Standby is not enough - computers can sometimes be remotely turned back on or booted up. If you're going to sleep or to work, and your machine isn't busy resequencing DNA or looking for extraterrestrial radio signals, then turn it off and unplug it. A power strip which turns off your monitor, speakers, etc., at the same time is the best thing to use.