You do not need to install Office 2000 to install the upgrade version of
Office 2007. Just insert the Office 2000 installation CD in the drive when
you are asked for a qualifying product during installation of Office 2007.
Since Office 2000 is compatible with Windows XP, you may want to understand
why your laptop did not "work properly" with Office 2000. Else, you may
have the same problem if you install Office 2007. Just a guess, but since
you just upgraded to Windows XP, you may need to upgrade some of your
hardware drivers or you may not have enough memory installed.