Man, D, stay behind and write "I must play awesome old games" 100 times.
GDI = "Allies"
Nod = "Baddies"
The Brotherhood Of Nod, specifically. Extremist lunatics who want to take over the world. GDI was Global Defense Initiative, or something similar. The GDI disc had the "good guy" campaign, the Nod disc the "bad guy" campaign. As I recall you need both to install the game.
C&C Gold wasn't as good as Red Alert, but damn if they didn't make it sweet anyway.