1) Install the attached "Arcsoft MMS 18.104.22.168.CAB"
2) Soft Reset
3) Go to Start > Settings > Connections and run "Connection Setup"
4) Soft Reset
5) Install the attached "thinkblu.Enable MMS Limits.cab"
6) Go into the MS Messaging Client > Menu > MMS Options > Servers and then click on your Network and look at "Send Limit" at the bottom and configure it your network's size limit (at&t's is 600kb)
7) Click "Done"
8) Click "Set as Default"
Also, if anybody has a newer version of Arsoft MMS for WVGA GSM devices please post it