Most people keep their PartyCAD data either on a server or on their local machine:
If you use a server
All you need to do is install PartyCAD on the new machine and then click Manage Locations and point the program to the server location. If you can, look at Manage Locations on your old machine before the move. Usually the setup will be the same on the new machine.
If you use your local machine
Look in Documents on the old machine. You will see a folder called My PartyCAD Files. Copy this folder to a thumb drive and from there into the same location on your new machine. You may wonder what is in the _Resources subfolder of My PartyCAD Files. _Resources contains your forms, templates and any My Library furniture you have created, so be sure to move this folder along with your actual PartyCAD projects.
If you ever need to search for PartyCAD files on a machine, use a search term of *.pcad and every PartyCAD project within the scope of your search will be listed.