Looks ok to me...I would recommend keeping proper indenting to make it easier to understand though. So something like this should work fine...

Code:
$USERNAMEPREFIX = SUBSTR(@USERID,1,2) ; can also use $USERNAMEPREFIX = Left(@USERID,2)

IF $USERNAMEPREFIX = "97"
   $INI = 'H:\LastLaunched.ini'
   $page = 'http://www.kixtart.org/ubbthreads'
   $lastlaunched = ReadProfileString($INI,'Intranet','lastlaunched')
   If $lastlaunched <> @Date
      $null = WriteProfileString($INI,'Intranet','lastlaunched',@Date)
      $ie = ReadValue("HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\IEXPLORE.EXE","")
      Run $ie+" "+$page
   Endif
ENDIF