What is a light, fast linux capable of being a dedicated media player?

Have got an old laptop I’d like to use a dedicated media player. Its got modest specs, having 1.1 Ghz processor and 256-512 mb ram. I’d like to be able to turn it on, and as soon as possible, have a media player with a media library available.
I was assuming a linux distro would be most appropriate, but which one?