I've recently installed outlook 2010, connecting to an exchange 2003 server. the problem i have it that outlook 2010 has major slow, connectivity issues, Usually resulting in have to kill outlook, and restart. I have make several changes to the outlook settings including:
Removed all addins with the exception of the exchange server add in
Disabled encryption between outlook and exchange via account settings in outlok
changed network security from negotiate to password (NTLM)
changed to excange cache mode
I stil experience the time outs with accessing calendars, and receiving/creating/sending emails