new install on AMD64 x86 with "slight" X-windows problem

Ok, so I finally got all the bits and pieces I wanted for my 64 bit box together and have run into a slight problem. My 19" Monitor is capable of displaying 1280x1024, but only @ 75Hz. Yast seemed to detect the correct frequency range while I was installing, but when X/KDE started up my monitor reported that they sync rate was out of range. I switched to a terminal and logged in then ran YAST in text mode, but seem to be unable to change the refresh rates reported that are probed. How can I change the default refresh rate that X/KDE uses? I amsume that there is a config file I can edit while logged into a terminal, but after (a very short) google attempt I could not locate an answer. thanks Lance