Even entourage 2004 only has limited exchange features: shared folders can contain only e-mails (not events contacts etc), you can't run multiple exchange accounts without it merging them (unless you set up a seperate identity), etc etc. Entourage 2004 is your best bet if you have to run exchange accounts, but ti still aint no fun.
And you might come across something called groupcal - -a piece of shareware to sync exchange accounts with iCal, but beware, its expensive, and last time i checked the developer hadn't been on the board or answered emails in several months.