The chat saga is long and frustrating. Here are my subjective observations on the current version of the widget -
* It is still pretty flaky, but an infinite improvement on the first version release.
* The problems are probably entirely the widgets fault, with its scripting not entirely following accepted rules and causing hiccups with later versions of IE and FF - which have both gone out of their way to adopt strict scripting standard enforcement.
The ones that have worked best for me -
* IE 6 (!). Not because it's inherently any good, but because its like a cat on heat and will take any script you throw at it without complaint. It is also the reason that so many botnets got entrenched.
* Google Chrome - I've been using build 22.214.171.124 and it is remarkably smooth. Unfortunately, it's made by Google so who knows what information is getting pumped back about your usage.
That's it. If you have complaints about chat, there's not an awful lot of good done by whining about it. Test drive other browsers and see what works for you.