Installing Office 2000 on upgraded machine to Win XP

[Phil]

I upgraded from Win98 to WinXP Pro, Office came with the
original computer. When starting an Office 2000 app.
Windows Installer wanted the original CD1.

When installer starts, I get this error from Windows
Installer:
"This patch package could not be opened. Verify the
patch package exists and that you can access it, or
contact the application vendor to verify that this is a
valid Windows Installer patch package.

How do I get Office 2000 installed and working?

Thanks, Phil