And where? Sig

The Quake source has VC++ project files, look that up at www.planetquake.com. Also, the Quake2 SDK, Quake 3 SDK (just released) and the Half-Life SDK all use VC++. You can get the Quake3 SDK at www.demonews.com, and I''m not sure about the Quake2 SDK, probably www.idsoftware.com. The half-life sdk can come from www.planethalflife.com.
Good luck

Last I checked you could also get the Heretic and Hexen source from Ravensoft. It might also be at www.softseekcom.

You can also get the full Descent 1 source code here: www.descent2.com/ddn/sources/descent1
the game is quite old but still good..

You can also check the Code Vault here on GDNet.

Kevin