Neither QuickRes nor Soft15kHz can change your mame.ini
Looks like you're probably running the correct drivers for that card; however from what I'm reading, the various "Mobility" Radeons had vendor specific drivers. Is this actually a laptop?
To your original question, bit depth and refresh rate (hz) have nothing to do with one another. It's like asking if the color of a fruit has anything to do with how much it weighs-- they are independent of each other.
I do not recall ever seeing QuickRes list the refresh rate in the listing, only the bitdepth. Maybe someone else can correct me on this. I see bit depth on my setup.
What I would recommend doing is cutting the computer monitor out of the equation all together. Install a program such as UltraVNC (
www.uvnc.com) that will allow you to control the computer over a network from another machine. This way you can change display settings even when the arcade monitor is displaying improperly.
I would do the following in this order:
Uninstall Soft15khz.
reboot.
Install UltraVNC, set up a simple password (like 'a'), and verify that you can connect to it from another machine and control it properly.
reboot.
Verify that UltraVNC has started up properly on its own after a reboot and that you can connect to it and control it properly.
Install Soft15khz, selecting only the 15kHz option.
Shut down the computer fully.
Unhook VGA monitor
Hook up Arcade monitor
Power the machine on.
When it gets into windows, connect via VNC and see what QuickRes is showing as available options.
Hopefully you can select 640x480 and have a proper display on the screen.
Once you've got it working that far, THEN we can see about getting Mame working properly.