Sure -- I have two problems. One is cvs related:
$ gmake -f client.mk checkout
checkout start: Tue Jul 11 16:11:21 EDT 2006
cvs -q -z 3 co mozilla/client.mk mozilla/build/unix/modules.mk mozilla/build/unix/uniq.pl
cvs checkout: existing repository /cvsroot/CVSROOT/Emptydir does not match /cvsroot/mozilla
cvs checkout: ignoring module mozilla/client.mk
gmake: *** [checkout] Error 1

The other, which I am more interested in solving is:
$ gmake -f client.mk build
/usr/bin/gmake -f /mozilla/client.mk build
gmake[1]: Entering directory `/c/cygwin/mozilla'
gmake[1]: /mozilla/client.mk: No such file or directory
gmake[1]: *** No rule to make target `/mozilla/client.mk'. Stop.
gmake[1]: Leaving directory `/c/cygwin/mozilla'
gmake: *** [build] Error 2

I am guessing it is a path problem, but I have been over the prerequisite stuff, and FAQs, and I got stuck here. I am trying to build the sunbird calendar.