I use AdiumX for all my instant messaging needs. It does moreorless everything you want it to do - connects to every chat service under the sun, endless customisation (skins, sounds, displays), supports Growl and more. And it’s slick, too. I love it.
But the only thing it won’t do is video chat. Which is a real shame as my new MBP has an iSight built-in. But if I want to use it, then I have to use iChat, but unfortunately I simply don’t know enough cool kids who actually use a Mac + iChat, so it’s pointless.
I’m not blaming the Adium guys - it’s not their fault, and they’re certainly doing their best to get something sorted out - but if anyone knows of a chat client which will enable me to use my iSight on the MSN chat service, then I’d love to know about it.
UPDATE:
Turns out I should STFW a bit more. aMSN has been around for a while and does video chat on MSN on the Mac. I’m a dumbass.