I like the Chat application very much because:
- The application is simple.
- Chat Histories are saved on Google Servers and available from anywhere in the world.
- You can access Google Chat from the Gmail web interface.
I followed these comprehensive instructions except that I wasn't able to get it to work with the servers they had listed. I used jaim.at for AIM and msn.jabber.anywise.com for MSN. Here is a List of Jabber servers.