I can tell you one thing I absolutely love Ubuntu for is its ability to take an old PC, and perform CPR on it. Perhaps something sold right at the dawn of XP, but with the service packs and updates it is not pretty much useless as an XP machine, say a late Pentium III, or really early Pentium 4, or just about any Celeron are good examples.

If it breaks your heart to just throw it out, perform CPR on that thing with an Ubuntu installation. I had a customer with a laptop, old Pentium III 933 megahertz, 128mb of RAM, acceptable to run XP on day one, but over the years with the service packs and security updates, it had become a pretty much useless brick, but it runs Ubuntu 8.1 fairly well, enough to at least get some decent productivity out of the hardware again.

So if you, or a friend of family have an old piece of hardware laying around collecting dust, that's an amazing place to start your ubuntu experimentation, it runs really well with fairly low hardware requirements. I'm not telling you it will run fun on an old Pentium pro, or even a 500 megahertz pentium 2, but if you have a Pentium III, early Athlon or better with 128mb of Ram, its a pretty decent experience when compared to a fully updated XP.