For Each myItem In Application.Explorers.Item(0).Selection
myItem.UnRead = False
This little macro marks the current selected item(s) read and moves them to the 'Archive' folder (that you will need to create at the top level).
I also added a button to run the macro and called it "&XArchive" so I can go Alt+X to archive the currently selected mail item.
Works for me..
Oh, I'm using Outlook 2000. You may need to change the macro for other version.
Let me know :)