Lookin for the right theme for my site

I want to have an event calendar and the event calendar needs to allow some users to add events to the calendar. BuddyPress Events Calendar seems to be the plug-in I want but I need to downgrade my WordPress version to 2.8.6 I’m running Arjuna Theme right now and the other calendars don’t seem to work right or maybe I’m doing something right. Please a point in the right direction would be appreciated.