What do you intend to use it for? It's pretty ancient, and even with the best CPU it can take, it's only going to be good for web browsing and light desktop usage. Don't expect to run modern games.
It uses a proprietary power supply, so you'll either need to lay the PSU in the bottom of your new case, unattached, or replace that as well. It's also limited to 4GB of RAM, which is pretty much the bare minimum for Windows 10. Honestly, sinking money into it sounds like a bad idea.