I wanted to spread the word on this. Some people have been having problems with NATO 2 and Minimal installs asking for the CD all the time. I found the problem. Here's the fix.  Either:  Replace your Constants.txt file in your Rainbow Six directory with this one:
http://people.we.mediaone.net/gpolk/gnn/files/NATO_200_CDFix.zip
or edit your Constants.txt file. Change the second to last line to read:

LABEL_NAME "Rainbow Six"

That's it.  If you want the details, the patch on the Eagle Watch CD appears to be bad in that it makes that LABEL_NAME wrong. The NATO 2 constants.txt file was
built with this wrong label, but it works fine with full installations, so I
didn't notice the problem.  BrownFoot was the trouble shooter on this one :)