Really depends on how much your monitor can handle, when you only see a certain amount listed when the "hide" box is checked then those are the ones you can use safely. Doesn't mean your monitor can't handle a slighty faster one. It also depends on what program you use to change it, when I change my frame rate using the normal way through right click, settings, advance, monitor. And If put it over 60hz ( for 1280x1024 ) thats how much it can safely handle, but if I put it on lets say 70, it will screw up my picture. But If I use a program called refresh locker (I don't know if it will work on non ati cards, it comes in a 3rd party driver pack) it can go all the way to 160hz without screwing up, but I don't feel safe with that so I put it on 75hz and I haven't had a problem yet.
You might want to get Powerstrip and see if you can change them that way.
http://www.entechtaiwan.com/ps.htm