You have a computer (a laptop or a desktop). Since it's a
machine you use often and don't tinker with much, it probably runs
Ubuntu Linux. Or, maybe, another distribution (like Mandriva 2008).
If it doesn't run GNU/Linux, I hope you're at least using BSD. If
not, stop reading right now!
"You also have a brand new digital camera, or a shiny new MP3
player. And you feel the dread: are those pure consumer oriented
pieces of hardware compatible with my machine? Will I have to pay
the Microsoft tax (and the required hardware upgrades) to get all
my photos from my last holidays, or to listen to Beethoven's fifth
sung a capella by lazy llamas...?"