On October 18th Ubuntu released 7.10 Gutsy Gibson.
Ubuntu is a Operating System like Windows or Mac OSX, but is free and maintained by the community.  It also run more efficiently on older machines than XP, making a great choice for that old machine your not using.
I upgraded from 7.04 Fiesty Fawn and it seems to be running pretty well.  It has better bluetooth support I can tell so far.
You can download and find more info here.