If I understand correctly, you have an HP Pavilion ZV 5000 laptop that does not run but has a 60 GB hard drive that has Windows XP installed and also has Office 2003 installed.
You want to put the hard drive from the laptop into an old desktop.
You have two issues: hardware and software.
The hardware issues can probably be easily solved (you would need something like this $10 kit --> http://tinyurl.com/d539pwf -- but read the comments).
The software problem is that you can't take an existing installation of Windows XP and completely change the computer hardware. If you try that, you have to do a reinstall of Windows before it will work.
If you have a generic OEM XP install CD, you may be able to do a repair install (saving the applications -- e.g. Office 2003), but the CD must be at the same or later version of XP (Home, Pro) and Service Pack level as the version of XP which is installed. You must also have the product key that goes with the OEM install CD (I think the key from the label on the HP will fail).
More likely, you will have to do a clean install, which will involve formatting the drive.
If you have the install CD for Office 2003, you can recover its installation key from the laptop drive before you install it in the desktop. Probably the easiest way to do this is to put the laptop drive in an external drive enclosure, attach that to a working computer, and use Magical Jelly Bean Keyfinder using its "Load Hive" feature.