You could also try out kmess
I even like kmess much more then the MSN6 from Microsoft
Both programs have support for the new SSL-login support, so Microsoft can't block them yet.
Imho Kopete is a bit messy, but it seams to support a lot of other MSN6 features already, and also supports other protocols (just like Trillian in the Windows world)
But seriously, if you even have to switch: try jabber
, because it's free, very promising, open source, and well supported by a lot of clients. If you need a client to convince the 'breezer sl***' (how we call them in The Netherlands .. hehe), I can recommend you rhymbox
, it's a jabber client too.