About a free C compiler, you may try the Microchip C18 student version.
http://www.microchip.com/stellent/id...&part=SW006011

i hate the microchip compiler but it's working. In another hand if you buy it... it will by far cheaper than Hi-Tech C.

CCS do one too. I just had a look to their website... seems to grow since last time i went there.