Any Intel-compatible processor should do. Actually, you can find a Unix that will run on just about any widely-used chip there is...

Like I said, if you are into the bleeding edge, you may have problems utilizing all of their features, but there is a good chance you'll find what you're looking for with Linux. Now, if you're going to drop a few hundred bucks on a bleeding edge video / sound card, you might want to check compatibility first...

But you'll find just about anything you want - Music, still graphics, video / CGI... almost all of it free for download.