Connecting to a network with potentially thousands of users, does pose security risks, however, there are some things you can do to minimize this.
EASY:
Connect to a server running Vworld (irc.cotse.com)
Vworld will hide your machine's address from other users
Don't use your real name/details
Don't accept/send over DCC to non-trusted parties
Patch your operating system to the latest service pack/kernel
Never IRC as root
Use a different password for services than you use for any other machine
COMPLEX:
IRC through a proxy/BNC
Run and maintain a firewall
Telnet - secure shell - BitchX - IRC