Still have message video mode not supported

wont be able to get another monitor soon and wanted to know about a way to adjust resolution/Hertz
when i go to the bios (so it doesnt go into windows and say video mode not supported w/a black screen ) and hit the menu button on the monitor it reads a 740x480 (or something like that--though i dont know if thats the bios's resolution or vcard's res) at 70hz and the optimal is 1024x768 at 60hz
however, the monitor menu does not allow me to alter res or hz
is there any other way to fix the problem wo/another monitor?
thats for any help.
(by the way its a win98 comp)