For those of you having problems using the fixed aspect ratio in nVidia cards, I have a solution that at least works on my laptop's GeForce440 Go (though I don't know how).
First, I have the
Omega Drivers version 1.6693 nVidia driver on a laptop instead of the standard nVidia driver. I don't really think that is necessary but I'm no expert.
Alright, first go to the nView display manager, which is accessible though Control Panel->Display->Settings->Advanced->Whatever your card name is.
Then, go to nView display settings (on mine it's also Device Settings->Device Adjustments) and select "Fixed Aspect Ratio" and confirm.
Normally, when starting an application under this setting, the screen will become garbled. If you let it run too long and hard quit the application your desktop will also become garbled, at which point you have to do a double ctrl-alt-del restart and hope that it doesn't carry over or becomes viewable enough to change the screen settings back or even go so far as to system restore or uninstall your display driver.
HOWEVER, I have found that I can actually use this setting as it was meant to be used.
After you change to fixed aspect ratio, before starting any program and testing it out, go to the Desktop Management tab and enable all the desktop management settings if they haven't been already. Then go to Hotkeys, which is under Desktop Management. Open the Display mode tab and select "Toggle LCD Scaling" and select Add. Then assign it to a key combination you don't use very often. Confirm.
Now if you have separate programs that allow widescreen stretching orrequire a centered output this hotkey is useful as is, but it has a much better use here.
Open up your program that you want to show in a fixed aspect ratio. If you've done the first part and you have my problem, the screen should be totally garbled with ridiculous scanlines. At any time you want, press the hotkey that toggles LCD scaling (that you specified) twice, so it is turned on and off.
If you have anything like my configuration, you will automatically be gifted with the black-side-bar display with the perfect fixed aspect ratio, no stretching involved. This will stick, probably, as long as the application runs or does not change its own resolution. If it becomes regarbled just do the double toggle again. And if you want to run centered, just toggle on and leave it.
My configuration may be different from yours, but I hope the screenshots will guide you to the analagous portions required for this function. I hope this information can be applied to the other cards as well if similar problems exist. I hope it works for you.
Edit: Oh yeah. If this solution has already been mentioned somewhere, I apologize. I am not exactly a driver expert and so the particular lingo used must have gone over my head. I just found this out by accident.