Help I need a Win ME product key to go with cd

I was recently given a computer to fix and use in my classroom at school. It was a HP 7960 Pavilion, Pentium 4 and it came with Windows ME. I have the ME cd , but no product key. I also have all the HP Pavilion support information numbers. I wasn’t given any software except the ME cd. The hard drive crashed and I put in another hard drive. However, I can’t install Windows ME because I don’t have a product key for installation.
Is there any support place that will give me the product key for ME since I have the computer it was installed on and the ME cd? I have already spent $70 on Ebay buying rdram to put in the computer. Before it was given to me, all the memory was taken out.
I really don’t want to spend much more out of my pocket. However, I would be willing to spend about $10 more if I could buy the product number. As a teacher I always seem to spend the majority of my money on computer stuff for my classroom. We don’t have any Windows ME computers at school . The only person I know, with WinME, lost the product key even though ME is still running on her computer.
I tried installing another hard drive that had Windows 2000 on it, and using it on this computer. But HP doesn’t recommend using Win2K on the HP 7960, and doesn’t have much driver support. My motherboard is a WMT-LX Rev 1.04 . I kept getting an error for a PCI controller when I used Win2K, so I disabled it and the computer works. I guess if I can’t get the product key for ME I will have to go with Win2K so that I can use the computer.
Any suggestions or help would be appreciated.

Claire