sven.

There is a small control panel which claims to be able to switch monitors to 50HZ.

SwitchRes X
http://www.madrau.com/html/SRX/About.html

I installed the demo once, and it did some really wierd things, and i couldnt find a way to uninstall it - so dont do this on a real system.

I also might have to make some slight software changes to run at 50Hz.