How to get the Windows Server 2003 vhd password?

Hi,

I had asked a similar question for SCCM 2007 R2 vhd, and I got an answer very fast, so thanks for the response!
(A follow-up question is: How can I activate the SCCM 2007 R2 vhd, since I do not have the product key?)

Now the question proper
-- I had just downloaded a vhd for Windows Server 2003, and had opened it with Virtual PC 2007 successfully;
    However, when I see the log-in page, I know that I do not have the password!
   I know it is no use to guess the pw, so may anyone be so kind as to tell me?
   Thanks so much!

Joseph