You can use ESXi free just to keep this "stored" as you said. Both VMs can reside on the same physical box. When needed, you can access the XP console, use your application and connect to the server VM. Download the free version, so you will not have any costs: https://www.vmware.com/go/get-free-esxi/
Also, if you need to consolidate physical servers into VMs, you can use VMware converter, also free: https://www.vmware.com/go/download-converter and will work with the free ESXi too.
Cheers