I don't really understand why ICQ isn't popular anymore. I loved it!
To me, chat hasn't really gotten better or worse over the years. Yes, there's more crap now, but that's all it is to me. That's why I don't think ICQ is obsolete for me. If I was stuck with an ICQ app from 5 years ago, and all my friends still used it, I don't think I'd care.
If you go to Adium -> Preferences -> Advanced -> MSN and check Show display names as status messages, that should solve your problems.
EDIT: Actually, what you want might be found at Adium -> Preferences -> Appearance. Click the Customize... button that's next to List Layout: and in the Contacts tab, check Show and you can choose how it displays users' statuses under or beside their screen names.
Reading through this thread I've learnt that Adium supports a multitude of different chat clients. But can I use it to chat to my brother when I'm using a .Mac account and he uses MSN? Or do I have to have a MSN account to chat with another MSN user?
This has nothing to do with Adium; multi-service clients (Adium, GAIM, Trillian, etc), although they allow you to have multiple services signed on at once, are not able to cross-chat between networks. Because of course to chat on a network, you have to have an account on that network.