Scaling has gotten much better, for the most part, its hard to tell unless you are really looking for it. Unless you are usuing a really low/odd resolution and stretching it out of ratio.
Here's how I get around using lower resolutions without getting bars and keeping hte aspect.
First off, l 1680x1050 is actually 16:10.. not 16:9 btw.. Some people don't realize this..
So, keeping to that ratio and doing simple algebra.. you can try to using custom resolutions such as 1024x640 1280x800, etc..(add then thru nvidia's panel) have either your display or vid card scale out (fixed ratio, or stretch, centered, it doesn't really matter since its still 16:10 so it will take the whole screen) Thats what I used with Oblivion to still keep the widescreen aspect without running at 1680x1050.. or other games that only recognize widescreen aspects only if the resolution is of that aspect.
Also, some games itself lets you force an aspect ratio on any resolution.. In that case, you can if you want, force say 800x600 to be stretch scaled on your widescreen.. Then force the game to use the 16:10 aspect.. End result, lower resolution thats scaled to fill your LCD, but still looks right becaues the game also realizes even though its a physical 4:3 aspect (for example 800x600), its being stretched to displayed on a 16:10 aspect on in game settings.
For Quake 4, I just edited the config file for custom resolution and set a flag to make things right.. google it. its easy to do.. two places to set horizontal and vert.. Then another setting or two to force an aspect. The latest patch, may or maynot have addressed this.