Re: When will the XPS M1730 fully support Windows 7?
Well it looks like your only option is to test some of the beta driver here: http://forums.laptopvideo2go.com/forum/159-19x-series-geforce-driver-releases/ I'm not sure if you've done this before. Just remember to download the modded INF file with each driver and replace with the one in the drivers files you download and read the posters comments for solutions before you try a driver.
Also you might wanna check out this link: http://xpsm1730.blogspot.com/2009/03/updating-your-video-driver-right-way.html for the right way to update nvidia drivers. You might have some older nvidia files that are messing things up.
On an unrelated note, today I checked out some of the windows 7 "optional" updates available for my laptop and I noticed a bunch of driver updates. After installation, it got rid of 2 out of 3 unidentified base system devices! I'm guessing the last one has something to do with dell media direct.