Outlook Express 5 on I.E. 6? won’t set!

I cannot set Outlook Express as default on Internet Explorer [in the “Tools, Internet Options, Programs tab, Email box] 6.0 service pack1. At this point the box gives me only two options: 1.a blank box [non editable], or 2.Microsoft Outlook [Office97 was installed, then uninstalled then reinstalled again]. All I want to do is:insert Outlook Express in that box! I heard comments about having to adjust the registry, reinstall O.E., or I.E. What should I do? I am on Win98….Any good Ideas are welcome!
Thanks
FV