Running XP SP2. Outlook 2000 SP3. IE7

I have Outllook 2000 installed on my PC and want to (once again) have it as
my default e-mail for Internet Explorer7.

My problem began after I launched Microsoft Outlook 2003, today. Thought I
might try the trial offer to compare '03 against '00 .

Therefore, after selecting Outlook 2003, "Microsoft Office 2003 Set Up"
lauched. The window asked for my product key. I entered the "Key" number
from my Office 2000, software. I Immediately received an error message
stating that I did not have a valid number. I selected the cancel button and
closed the window.

Now each time I open my browser click on the mail icon - "Microsoft Office
Set Up 2003" launches.

What steps do I take to stop "Office Set Up 2003" from launching? I want to
revert back to Outlook 2000 as my default for e-mail.

I've Tried: ToolsInternet OptionsPrograms and Selected: Microsoft Outlook.
Unfortunatly, after selectin the "apply" button and clicking "ok"-"Microsoft
Office Set Up 2003" still launches.

Thank you.