there is a refresh rate, for every monitor ever, unless its an old fashioned picture frame, but thats not a monitor. i don't see a refresh rate specs on the site, but i would figure from someone elses comment that you should set it to 70hz, that, or get a new gpu that can support it. if the refresh is good, then check you resolution, a low res could put strain on the eyes
edit: just a little fact on lcd vs crt. lcds have a set number of pixels, unless your resolution is set to that amount, or something exactly similar so that the pixels wont overlay to another pixel, you will get optimal quality. while in crt displays, the pixels actually change size and pitch to the resolution that it is ran at. in short, if you are not running 1920x1080 on your current monitor, you won't get great image quality