There are less expensive ways to run a hosted OS on someone elses computer, too. Damn Small Linux and Puppy linux can both be installed to a thumbdrive, then booted on a host computer. You can get most of the functionality of the Blackdog on a $30 thumbdrive. They both fit on a business card CD-R, making them easy to play with, without much commitment.
I find DSL to be a quite capable OS. It jumps on the internet without configuration (dhcp), and can mount windows drives on the host computer, making it great for disaster recovery.