FoolSaver

Why bother with this when you can throw gobs of money at the real thing - Virtual PC That way you can have the sluggishness and the complete effect. If you don't want to make a statement that you think "out of the box" then do it the right way - buy a $250 screensaver. If nothing else it is a good way to justify buying more RAM for your Mac. You might even be able to write it off on your taxes!

Even better: install Tigger and you get all that lovely Microsoft sluggishness! What are you waiting for!?

To further the illusion, try out this widget: http://forums.macnn.com/showthread.php?t=266416&highlight=BSOD Hit F12, and behold the blue screen of death on your Mac!

Put this as your screensaver and use ShapeShifter or ThemeChanger with a Windows-esque theme such as Mac OS XP 2.5 (http://macupdate.com/info.php/id/13995), hide the Dock, cover your Mac logo somehow (I have my G4 tower under my desk anyway), use Office 2004 with Entourage 2004, and you might be able to convince people you're using a PC. No, wait, you'd have to pretend to have your computer crash way more often, fake the occasional BSOD, and curse at it... (Warning: the Mac OS XP 2.5 theme may not play nice with Tiger (see the comments for it; hopefully a 2.6 or 3.0 version will come out), but we still use Panther where I work so we can use ADmitMac 2.1 on our Windows Server 2003/AD network) as ADmitMac 3.0 for Tiger is still in beta.)

The Horror! The Horror! No, actually it looks kinda cool ;)

Screenshot: http://www.kainjow.com/images/foolsaver.jpg

Screenshot? No screenshot = no download.