<p>I'm new to the VxWorks environment, I'm wondering what C and C++ compilers are available for use with VxWorks?</p>

As far as i know Tornado VxWorks IDE using gcc toolchain.
Any way i suggest to use the compiler provided by WindRiver (which i believe their version 
of gcc)  to avoid compatibility problems. 
It's probably worth to menation the VxWorks version you having in mind.
I guess gcc version will be depend on VxWorks version and probably on target platform.