I switched to Macs at home in 2006 after using PCs since 1981. I've used Outlook since it was first released, and still use it at work. When I went Mac, I used Entourage as well, at first, given my comfort with Outlook.
I quickly realized that the MS implementation of Entourage (and Office generally) was woefully less sophisticated and feature-rich than than its Windows software. It also did not play as well with other Mac programs as I would have liked (sync'g in particular).
Therefore, I stopped using Entourage and now use Apple's Mail, iCal, and Address Book programs. It's nice having all that in one program (as in Outlook or Entourage), but Apple's integration of these three programs makes it pretty easy to go from one to the other (or have one access the other), and they all integrate with any other Mac program that needs that data (and with synchronizing through .Mac or other iSync enabled programs).
You might want to consider trying the Apple programs and see how you like them (they are also considerably less resource intensive than Entourage, which currently is not a universal program so it's running under Rosetta).