I wanted to document a few steps to getting IRC working on windows with notifications. Pidgin is a decent client to connect to IRC on Windows, though some prefer using mIRC. Unfortunately for windows, there's not a well established notifications framework like there is on the mac (growl) or linux (libnotify).
So to start, download and install the following:
Growl for Windows
Gnarly (Growl->Snarl bridge)
PidginSnarl (pidgin notification plugin)
Once all these have been installed, add an IRC server to your pidgin installation, such as irc.freenode.net.
Growl needs to be started and in the preferences, you'll likely want to load it at startup.
You'll likely have to restart pidgin after installing the pidginsnarl plugin. After restarting, go to Tools->Plugins. There will be two that you'll want to enable:
Then configure MessageNotifications - enable notifications for Chat, and then if you'd like have it notify you only if someone chats to your username.
Then go into Growl into the Applications section, click on PidginSnarl. Configure the Chat Received notifications to how you'd like it.
You may want to configure other things like logins and logouts and status changes to not notify you as well (disabling them).
That's it. Whew, kinda complicated on windows, but that's it.