I'm using MPLAB/C18 for the pure C stuff. You should give that a try.
A good place to start is with the vex Starter Code (just like the default program for the full-sized robots). It's on the Vex downloads page at:
http://www.vexlabs.com/vex-robotics-downloads.shtml
The EasyC v2.0 (not the one that comes in the Vex programming kit) can also be a good starting point. You can use all the standard functions, but add some real C code of your own. It helps you avoid some of the C syntax errors you see a lot of when you're just starting out.
I wouldn't try programming from total scratch just yet. You need to get used to how things work and relate in working code first, so start with something that works and try making changes to it. Then you'll get an understanding of how things can go wrong.
