there are some serious considerations when choosing a C compiler. I lean heavily toward Hitech C because it relies more on bitwise operations then a true C compiler. ANSI C doesnt have much as far provisions for bitwise operations that microcontrollers utilize heavily. CCS is also a good choice for free/low price software, there are subtle differences between the two, but both are good compilers to learn how to code micros in C, and there is some value in understanding the differences however minor they may be.
Check out the first couple of tutorials in gooligums C sections, he does a nice job of pointing out differences in compilers.
