setting display refresh rate

[cty]

Hi!

I have a small problem regarding changing the refresh rate
in fedora 1.

The redhat-config-xfree86 utility (version 0.9) doesn't show
up an "Advanced" button like on some RedHat versions.
I've put a modeline in the xf86config file, filled with data
generated by an automated web-form.
But the new display mode doesn't appear in the graphical list, I can't
choose it as default mode and the ctrl-alt-+ combination is
also useless.
My video card is i865, on Windows XP it displays the needed
resolution/refresh rate correctly.
xvidtune says "the video modes are not tunable on this chip" (intel 
865).

I've spent a whole day experimenting with this and my monitor
is still on 60Hz...

What should i do?

Thank you in advance, Kovacs