I use Outlook Mobile Access as well, both on my work Exchange box and my home Exchange box.
I'm not sure but i think its only on Exchange 2003 servers? I know both of mine are.
Rather than hitting
http://servername/exchange, you'd want to hit
http://servername/oma/.
Give it a try! It's a nice simple text-based interface. Very quick and very easy to manipulate.
Jason