Speaking as a highly paid IT consultant

... this stuff NEVER happens to me (knock on wood and spit three times).
Never ever click those popups. Never EVER!

First line of defense - a properly configured firewall. If you're running XP or god forbid, Vista, get Comodo Personal Firewall Pro -
it's free. Make sure you read about before installing and you how to use it first (it's easy) - don't let in/out connection requests unless you know what's doing it. Disable the Microsoft built-in firewall. If you're running Some other version Win2K etc., use Online Armor - it, too is free.
2) NEVER connect to the intertubes using the default admin account - unless you're doing a dreaded Microsoft Update. This generally happen on Tuesdays.
3) ClamWin anitvrus -
Free and open source antivirus goodness! Forget about those corporate av programs permanently.
4) Firefox browser with NoScript extension. Enable JS script and other plugins only when needed. Do not accept cookies by default.
5) Create or use the guest account to run your browser. Use a regular account only when needed. Right click and select 'Run As'
6) Create a new administrator account. Disable the default admin acount.
7) Don't send or receive HTML email - use Thunderbird for your email client - from the same folks as Firefox.

Disable 'Services' which are not needed. Visit grc.com for some very helpful tips.
9) in Firefox menu for Tools | Options select the Content tab and check the 'Block Popups' Firefox will alert you when a popup tries to open and you can then decide if you want it to or not.
10) Buy a cheap external hard drive or even a large capacity thumb drive and BACK UP IMPORTANT THINGS!
11) Learn how to use System Restore.
12) Show someone how to do all this once you've figured it out.
![Drink up [B-o]](./images/smilies/drinkup.gif)