Not a silly question, actually.
Civ3:Complete is fully patched. There might be a few discs out there that aren't fully patched. I understand there was a small run that didn't have every patch. But usually it's patched.
Now, you're thinking to yourself, how do I know it's patched? Easy! On the bottom left of the menu screen, you'll see a number. If you're playing "Vanilla" Civ3, it'll be 1.29f. If you're playing PTW, it'll be 1.27f. And if you're playing Conquests, it'll be 1.22.
So you shouldn't need to patch it.