Command & Conquer For Free!
EA is celebrating the 12th birthday of the first Command & Conquer game by offering it as a free download. The version offered is the Windows 95-compatible "gold edition" and comes on the GDI and Nod discs. There are install instructions as well as it seems there are some extra steps necessary to get it running under Windows XP.
Since the site requires JavaScript enabled to view the text, and I know there're lazy people out there, here are direct links to the ISO images and install doc:
Update:
Apparently the game runs on Wine as well but not on Vista (thanks 0bsolete).