If you use linux as your desktop, I'd recommend learning bash. That will give you a good grounding on basic things like conditionals, loops, variables, etc. Eventually that will run out of steam and I'd recommend picking up a more powerful language that has nice things like solid libraries and isn't saddled with trying to be interactive. Examples would be python, ruby, or groovy.
I would stay away from C, etc unless you want to deal with hardware eccentricities. It is ABSOLUTELY worth it once you have a good grounding, but speaking as someone who learned C, but couldn't code his way out of a paper bag until he learned other languages and then came back to C, I highly recommend not picking it up until you've mastered one of the higher level languages.