When you install Office, you have a choice as to which components you want to install. Just don't install Outlook, and it cannot become your mail client.
If you want Outlook for its other features but not for mail, just open Outlook Express -- a box should come up asking if you want it to be your default mail client. Click Yes and it will then handle your mail.
In my opinion, Outlook is better than Outlook Express -- but you must have a reason to prefer the latter.
Hope this helps
Frank
The last time I installed MSoft Office '97 on my Win2K it overpowered Outlook Express as mail handler. I now have WinXPPro and want to install MSoft Office 2003 Pro for its other functions but don't want MSoft Office to remove OUtlook Express as default mail handler. What do I do? Thanks, Jim

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