Enable the Change Password feature with Outlook Web Access on a Windows 2003 Exchange 2007 Server

First Step create the IISADMPWD virtual directory, do the following:

1. Click Start, point to Programs, point to Administrative Tools, and then click Internet Services Manager.  
2. Right-click the default Web site, point to New, and then click Virtual Directory.
3. In the Virtual Directory Creation wizard, type IISADMPWD in the Alias box, and then click Next.
    
4. In the Directory box, type c:\windows\system32\inetsrv\iisadmpwd or the location where your hard disk is your default hard disk, and then click Next.
   
5. Verify that only the Read and Run script check boxes are selected, such as the ASP check box, click Next, and then click Finish.
    
6. Verify that the IISADMPWD virtual directory has only basic authentication is set
   
7. If you use Windows 2003/IIS 6.0, verify that the application pool is set to MSExchangeOWAAppPool
    
8. Register the IISpwchg.dll file in the Iisadmpwd directory:
   Click Start, and then click Run.
   In the Open box, type the following, and then press ENTER:
   regsvr32 c:\windows\system32\inetsrv\iisadmpwd\iispwchg.dll
9. Configure the PasswordChangeFlags property in the metabase to make sure that the Password Change functionality is enabled:
   Click Start, and then click Run.
   In the Open box, type cmd, and then press ENTER.
   Locate the C:\Inetpub\Adminscripts directory.
   Type the following command, and then press ENTER:
   cscript.exe adsutil.vbs set w3svc/passwordchangeflags 1

   0: This is the default value. This value indicates that you must use a Secure Sockets Layer (SSL) connection when you change the password.
   1: This value permits password changes on non-secure ports. This value is useful if SSL is not enabled.
   2: This value disables the Password Change functionality.
   4: This value disables the advance notification of password expiration.

10. Do not forget to enable Active Server Pages.
     
    Source http://support.microsoft.com/kb/297121