Unfortunatelly latest Catalyst for Windows 7 and Windows XP does not allow for forcing custom refresh rate. On linux it works flawlessly, it ignores EDID so You can easily change rate to 50Hz with xrandr. On Win the only modes allowing for PAL are the HD, not standard modes
. You could use PowerStrip, but it's quite dirty solution and push You to use third party commercial soft to obtain basic feature.
Maybe some world wide message shoud be sent to Ati/AMD and/or LCD monitors producers with this request. Australia's and Whole Europe standard is PAL and most of modern LCD displays correctly this mode when forced. I had to use CRT monitor and set it to 100Hz to have fully smooth PAL movie playback.