What cvs version and client are you using?
For an example TortoiseCVS will by default ignore files and folders that match the following cases:
core RCSLOG tags TAGS RCS SCCS .make.state
.nse_depinfo #* .#* cvslog.* ,* CVS CVS.adm .del-* *.a *.olb *.o *.obj *.so *.Z *~ *.old *.elc *.ln *.bak *.orig *.rej _$* *$
"I may not have gone where I intended to go, but I think I have ended up where I needed to be." --- Douglas Adams