For instant messenging, use Gaim, it's multi-protocol, it will work for MSN, Yahoo, Googletalk, AOL, ICQ, IRC...etc...
See it here :
What Is Gaim? - Gaim
For MSN fans, either in Mac OS, Linux or WIndows, a great alternative is aMsn, an open-source clone (you won't get viruses or spyware with it)... See it here :
Alvaro's Messenger
And yes, Rocky, things seem to work just fine with only the 200's serie of DNS
