Let's Make Robots!

Analog/digital signal output from laptop?

Apologies if this has been covered here before, but so far my searches haven't pulled much up.  I'm thinking of a few uses for an old and somewhat defunct laptop I have lying around, and most of them would involve sending information from the laptop to control components like motors directly.  (The idea is appealing since it'd be using the proessing power of the computer for most things, and also because I have more experience in that realm... not to mention potentially being cheap, since I already have the computer!)