So I insert my CD and run the setup- after it does that 'preparing setup wizard' thing for a sec a blank error message pops up (all it contains is the red error image and an OK button) and then it crashes.

Thinking maybe my CD was screwed after years of neglect, I downloaded an ISO version of the game to try. Mounted CD1, ran setup and the same blank error occurs! I've tried changing the setup to win98 compatibility, I have all of the win XP service packs and compatibility updates, but two separate versions of the install (one legit one not) have come up with this error and not allowed me to even start installation. What can I do?

All help would be appreciated!

Sounds like Nomad is being blocked by your computer's virus protection.