If setup correctly, yes. (as in opening the dcc ports you wish to use and putting those in mIRC's options under file/options/dcc/options and of course allowing mIRC and server ports as well as port 113 for identd) Everyone has their own fav regarding firewalls, personally i've been using
ZoneAlarm for several years. You can find a couple others at
DALnet ezine resources , i think they have links to TIny and Secure.
For winxp users who need help setting up that firewall to work with dcc, see
Toidy's tutorial