Mac OS X,  Ubuntu,  Windows XP

Dell Mini 9 and Mini 12 -> Hackintosh

The Dell Mini 9 comes with a small solid state drive, not a massive amount of firepower and running Ubuntu, but for $199 starting you can change all that (and the color) and still get away with an inexpensive and ultra-light system for less than $500.  The Mini 12 starts closer to the $400 range, but comes with a lot more features (and weight).  Why should this matter much?  Well, they’re now on the hackintosh list, meaning you can install 10.5.5 on them. Imagine a less pretty, less flashy MacBook air, 64 GB solid state drive, 2GB of RAM for about $400 (plus Leopard license).