chat drupal Chat module

Hi Guys,

Can anyone recommend me a good chat solution for Drupal 6. I am trying to evaluate different solutions like DimDim, 123FlashChat Server, avchat(avchat.com)..

Has anyone used any of these solutions.. Will U recommend any?

I will be using this for a Learning Management solution. I would like to host online presentations, do whiteboarding, have the ability to control the time the chat sessions are on; All chat sessions will need to be stored and indexed for later retrieval. I will be using the apache solr module. That part seems to work fine.