If you do not find a PC based unit, I would suggest checking out a "Linear Logic Scanguage" made in Mesa, AZ.(
www.scanguage.com / 888-831-2845). It combines the scan-tool-code-reader/ digital-guage-readout/ trip-computer. It is CAN capable as well as OBD II, and it is stand alone (w/o a computer) for probably less $$ than a PC based unit. I find that it provides me with a great deal of diagnostic data, provides ability to reset trouble codes, but it is not a replacement for the GM dealer programming & test station.
Hope you find this helpful, and Good Luck!!