Sadly, the list has been removed in Windows Mail.
You could put the Contacts in the Sidebar, via the Windows Orb (Start) > All
Programs > Accessories > Windows Sidebar then add the Contacts (and any other
gadgets you want) by clicking the plus sign at the top.
Now click on the Contacts ‘shaded’ box and drag it to the Desktop to give a
bigger and better display as an ‘open book‘. Just double-click an ID to send
mail.