A great place to start is to pop a live distro (knoppix, ubuntu live, etc). Most of the GUI stuff should be fairly intuitive. Learn the terminal. There are lots of places online where you can learn shell commands and stuff. Most Linux programmers do most of their work on the terminal. If you really like it try to install it. I started with a dual boot, moved slowly to more and more linux, then eventually destroyed my windows partition to have some more storage space.