ChatStat is really good. It is free for the basic functions, but you can pay for more advanced functions. http://www.chatstat.com/
I've a little confused by your question but we make use of kayako live support for our live chat system.
i dont think chat stat can fit into small width like Meebo or can it? i think with ChatStat the user needs to open a new window... is the ChatStat is an external program that i use or just i logg in to the website to see messages? the kayako is too big with a lot of features we don't need now.
You may want to check out a few alternatives like liveperson etc. They have a very good live chat software.