Thanks to Maciej for this one:

The fix presented below include only editing of windows registry hence no need of running any third party apps of unknown origin.

Theoretically this fix should be display-driver/adapter indenpendent since it modifies settings for the monitor rather than display-drivers/adapter itself.

IMPORTANT
Before making any changes make sure that your monitor supports the refresh-rate--resolution combinations you wish to use. Use this fix at YOUR OWN RISK.

Assuming that you have installed your monitor correctly (the monitor driver supports the desired vertical refresh rate, here 75 Hz), and you have a "normal" system (no multi-monitor support enabled etc) do the following:

Open regedit and find this key:

[HKEY_LOCAL_MACHINE\\\\system\\\\CurentControlSet\\\\Control\\\\Class]. Expand the "class key", you will see a bunch of keys similar to

{1113E534-EAF87542.....}

If you select one of them you'll see some values. There should be a string called "Default" or "Class" or both of them, saying what kind of device it is, like "Modem", "Keyboards" etc. Find the key that has a string value "Class"="Monitor".

Expand that key and there should be at least one key, typically "0000". Might be more, in that case you'll have see which one is currently in use. Just modify them one by one.

Start by expanding the "0000" key, there should be a key "MODES", expand it, now you should see a key with your monitor's max resolution. Now, suppose that you want a 75 Hz vertical refresh rate in resolution 1024x768. Add a key in "MODES" called "1024,768". In the "1024,768" key, add a String value

"Mode1"="75-75,75-75".

Now if you open "Display properties" (right-click on your desktop) click the "Advanced"-button and go to "Monitor" tab you will be able to select only one refresh rate namely 75 Hz. Provided of course that "0000" key was the key currently in use and that "Hide all unsupported modes" checkbox was ticked. Repeat the procedure for all refresh-rate--resolution combinations you wish to use.

Go to "Display properties->advanced->monitor" and select the refresh rate, here 75 Hz.
Basically what this fix does is setting the lowest refresh rate supported by your monitor to the one you wish to use. Now all games should run on the specified refresh rate regardless if they use Direct3D or OpenGL.

That should work in XP too.

Thanks to Neil for this update:

The new 40.72 drivers (beta 2000/XP) have an option within the Direct 3D properties to assign refresh rates for different resolutions.

I am sure this will still be in the WHQL release.