It’s a great machine to learn on. Build yourself a web server or something like that. You don’t know what it can do until you push it, and you’re not out anything by taking it to its limits. If it has something like a Core 2 Duo you could even run KVM and launch a virtual machine to learn about that process. Old hardware is meant to be run into the ground and you’ll learn a lot in the process, including getting a feel for how much hardware you really need to perform the tasks you want. (I literally just retired a rack server this year with a Core 2 Duo and 8GB of memory, which was used to run five VM servers providing internet services.)