You could select whatever midi and audio tracks belong to the drums you want to save and use in another project, then create a Track Template. This would take all of your selected tracks, any associated routing assignments, any associated soft synths, and settings for all of the above, and save it to wherever you would like. Then you could insert from that same Track Template later, in another project.
The thing though, is that the midi DATA for any midi track included in the selected tracks that MAKE the Track Template will NOT be saved as part of the Track Template.
That is not a problem, however, as you can SUPER easily take the midi data for any track, highlight all the midi clips in that midi track, then simply click and hold on that midi track and drag the selected clips off of Sonar to your desktop, and it will create a midi file of that selected data - just like that. Poof - Ta Da. (I got married like that once - still don't know what hit me).
Then, if you wanted to import that midi data back into your new project, just insert your track template first, then click on the desired midi track and click on File>Import>Midi and navigate to wherever your saved midi file lives and double click on it to bring it in.
I hope any of that helps,
Here is a link to Sonar doc for X3, working with Track Templates:
http://www.cakewalk.com/Documentation?product=SONAR%20X3&language=3&help=Arranging.08.html Bob Bone