WinXP HE…Can’t Logon

I need some HELP BAD !!
Here is the deal…I have a Compaq Celeron 1.4GHz, WinXP Home Edition, 128MB RAM, 40.0GB HDD, CD-ROM, CD-R/RW.
A client gave me the PC to install the CD Burner, so I did. The problem is, my client’s daughter put a Password for all the Users…the WELCOME screen is NOT used. She doesn’t remember what PW she used, they were written down on a paper and that paper was lost. How can I Logon? My Task is to Logon by-passing the PW, then disable the PW’s so most importantly my Client can use the PC.
I don’t have a XP HE disk, I DO have an XP PRO disk though. I also have 2 or 3 Compaq Rescue Disks that my client gave to me…
HOW CAN I LOGON AND DISABLE THE PW ????

MY CLIENT ALSO DOESN’T WANT TO UPGRADE TO WINXP PRO, SO THAT WAY IS OUT OF THE QUESTION.

PLEASE HELP ASAP!!!!!!!!!!!!!!!!!