Wirelessly posted (htc Pocket PC: Mozilla/4.0 (compatible; MSIE 6.0; Windows CE; IEMobile 8.12; MSIEMobile6.0) Sprint T7380)
If you click on your clock and go to where you set your alarms click on the options tab at the bottom and check the box that says "Sound Alarms Even When Device is set to Silent or Vibrate."