http://docs.us.dell.com/docs/monitors/p991/en/index.htm is the address of the whole manual, online. I would figure 85 hz and 1024 by 768 resolution, that's what I use on my similar Sony G400. In Win XP,Right click your desktop in a blank area, choose Properties, Settings tab, Slider at 1024 by 768, advanced,monitor tab, highlight desired rate from drop down. Hit apply, if windows asks if you want to keep the setting say yes or no as needed. Win 98 is similar.

That did it.

Thanks!

You're welcome!