Outlook XP help!!!

Im using Windows Xp and Office XP.
I did fresh install and everything works fine except for when I open up Outlook, it always asks me if I want to make Outlook my default manager for mail, calendar, etc…. I click yes. But it always asks me that everytime I open up Outlook. Im using Outlook not Outlook Express and I retrieve my mail from an Exchange 2003 server. How can I make Outlook my default manager. Also, my task reminders in Outlook will automatically pop up on my desktop!!! How can I make the task reminders go straight to my task bar instead of popping up on my desktop in multiple windows. THANK YOU FOR YOUR HELP!!!