http://humorix.org/slogans/
Some of my favorites are ...
Linux: Because a PC is a terrible thing to waste.
Why use Windows, since there is a door?
Computers are like air conditioners -- they stop working properly if you open WINDOWS
Do you remember when you only had to pay for windows when *you* broke them?
National Weather Service advice for those threatened by severe thunderstorms: "Go inside a sturdy building and stay away from WINDOWS!"
Your mouse has moved. Windows NT must be restarted for the change to take effect. Reboot now? [ OK ]
If Bill Gates had a nickel for every time Windows crashed... Oh wait, he does.
Gates' Law: Every 18 months, the speed of software halves.
With Windows Millennium, Microsoft was able to get the boot time down to 25 seconds. That's almost as short as it's uptime.