We Have Migrated our system from small business 2003 to small business 20011 using exchange 2010
there is varies versions outlooks working 2003/2007/20010 on windows XP and 7 workstations
Most are in the office on a 1 GB Lan but a number run across a software VPN
some not all Outlook 2007/2010 versions keeps asking to be login some regular, some only every couple hours
OWA works Fine no issues