Nice!

Do you know how much server load this adds to my forum?

Due to an exploit that has been brought to my attention by my security team, I would recommend uninstalling PJIRC and using LightIRC. PJIRC is no longer supported by it's creator and therefor the exploit that was discovered may not be fixed. However I have ported all the features over to LightIRC to integrate that into vBulletin. With this I have brought in the request to use vBulletin passwords as the password to the IRC server. LightIRC is updated often, and with each update I will be updating the Product. Now you will not have to worry about any annoying Java popups to use the chat. It's quick, sleek, and did I mention quick? Because it is.

Anyway any problems feel free to report them to me. Make sure you uninstall PJIRC, delete your IRC directory, and the chatbox.php. Now upload everything in the upload folder back to your vB directory, install lightirc and set your settings. :)
Not many as all the load would be put on the IRC server unless your server is the IRC server.

Got this

getting the exact same issue as solarboy

I'm getting a password mismatch error when I try to connect to my irc server, even though my server doesn't use passwords and I don't have the password option selected in the plugin. It connects to the default irc server without problems. Other irc clients connect to my server without issues.

One difference I noticed is that my irc server only has an IP address (no associated domain); could that cause problems?