People here think that mIRC is a P2P program.... well get over it. It is made for chat.
If you afraid of being infected with trojans and spywares, then I suggest you don't to use mIRC or join IRC channels cause you seem to be a little n00bish.
Lots of newbies catch those torjans on IRC Channels just because someone tells them:
"Do you want to be an IRC OP ??"
"Do you want to download Matrix 2 ??"
Then write This....Bla Bla Bla.
Or people who enable the auto DCC get files from infected people and then they run it themselve and also get infected.