I got the product key with the packaging, but no admin password. I found a ms not (312149 I think) that showed how to go into Administrative Tools and set security to automatically logon as admin during recovery. I'll try your link too (before formatting

).
I was going to use the recovery disks that came with the PC so I should be ok there. My brother gave me this machine when he switched over to a mac

so there are one or two bits of its history I'm unsure about.
Cheers
Liam