The PSP slim definitely has a TV-out port, I'm not sure if the older version has one.

It will output 4:3 and 16:9 and you'll need a TV that supports 480p. You can get Composite, S-Video, Component and D-Terminal leads. It works with all media, though last I'd heard games aren't displayed full screen for some reason.

Unless you live in Japan (where D-Terminal connectors are common) I'd probably go with a component lead because of the higher quality over S-Video and composite.