4. Blue Screen of Death Screensaver

To further remind Windows users of why they should , there's also the ever-popular . Slip it onto your victim's computer and then sit back and wait for the groans of agony! In no time at all they'll be begging you to help them install Ubuntu instead.

5. Mess with Their Desktop

Always fun for users of either operating system is the old trick of taking a screen shot of the user's desktop, packing all their icons into a single folder (or temporarily disabling them) and then setting the screen shot as their desktop background. Hours of entertainment are in store for them--and you--as they try in vain to click on those static icons!

6. 'Do Not Fool' Add-on