Find the file with an extension of .wab on the old hard drive. It should be username.wab, whatever name you had as the user on the old system. Copy that to the XP machine, putting it in the C:\Documents and Settings\username\Application Data\Microsoft\Address Book folder. Rename it to the new username if you used a different one on the new install.
Alternatively, if you can boot that hard drive on the same system, you can just export it from the file menu (just make sure you select ALL the fields to export, and send it to a CSV file). Then import it on the new system.