Count me as another vote for JiveTalk. Good user interface, works well with all my IM accounts / services, I can leave it logged on, running all day without a problem. Has worked perfectly for me. Highly recommended.
another vote for jivetalk - especially love that when i leave it logged in over night it doesn't 'pretend' to be connected, it really still is live and working. so fast and supports file transfer - amazing tool for the price. allows me to have freedom from the desk and spend more time with the family and yet not make our programmers have to wait for me to get back to give them real time answers. love it. when i leave work, i just log on to jivetalk and set my away message (great feature) and also when i leave for lunch or quick breaks.. keeps me connected with no issues.