I'm trying to change my Xbox's 360 Slim display settings from PAL-50 to PAL-60, but I can't see those options in the settings menu. I've tried connecting my Xbox to the TV via the original composite cable (it doesn't have a switch on it) but I still can't see that option!
When you choose a new display setting it tests pal 60 and pal 50 and asks if you can see the displayed image.
Try changing the setting from widescreen to 4:3 and back. It certainly asks when you change resolution from 720p to 1080i/p as I did that recently.