Outlook/Lotus Notes meeting

I have two users one who is using lotus notes and the other is using microsoft outlook 2003. The user with lotus notes is able to set up a meeting request in their calendar and invite the outlook user and it shows up in outlook like a normal meeting request and is added to the outlook users calendar. The outlook user would like to be able to set up a meeting in her calendar and simply add the lotus user as an invitee, and have it show up as a normal meeting for them. Currently the outlook user has to generate an email and add a .ics file attachment for this to work. Im looking for a setting or configuration that could possibly make this simpler for the outlook user.