IM Client app that works!

I'm on XP and am looking for an IM client that works well with MSN and AIM with all the features supported.

I've tried Trillian and it doesn't seem to support everything well.
Any other suggestions?

gaim? might not have every single feature you're looking for but it works with a bunch of different IM providers and it's worth checking out.

gaim.sf.net

edit: apparently it's been renamed to pidgin. check out http://sourceforge.net/projects/pidgin/