I am having this same problem. Here are my details.
I have an nForce 2 chipset mobo. The latest drivers are 5.10 for XP, however they work in Vista. They do NOT work in 7. I have also tried the 7.x branch for XP and the latest nForce 15.x branch for Vista, even though they do not support nForce 2 officially. Neither improved my situation.
I've also tried all the stuff in this thread and others with no luck.
Device Manager complains the driver cannot start (error code 10). I have checked the appropriate Microsoft KB articles and they are useless. The built-in troubleshooter in the network tray icon is useless, as well as in the Devices and Printers menu.
Error Log contains no warnings, errors, or critical errors about the driver that I can tell.
I started the driver myself using sc.exe. It runs. And yet Device Manager still complains it won't start, even as it is running. The driver doesn't stop or crash, which should mean it's working... but I can't use it.
I have tried uninstalling the device completely and reinstalling it both using the nVidia installer as well as directly installing the drivers using the Update Driver wizard. I tried both methods using all three versions of the driver.
The last thing I have yet to try is a suggestion from someone to use a program called DriverMax to export the driver from my working XP install of the driver, and import it into 7. I am not optimistic about this solution (and I'm not sure it's worth the trouble to try ATM, next time I happen to boot into it I will).
Waiting for proper Windows 7 drivers is not an option since I'm still waiting for proper Vista drivers.
Other non-working devices include a PCI Simple Communication device or something (I forget the name, and I'm not rebooting just to check) which is probably my modem, and some other stuff for my TV tuner. I don't care about them right now.
What really gets me mad is that no Windows OS properly installs my ethernet driver automatically... it always has to be done manually, so if I forgot to download the drivers before reinstalling I've got to jump through tons of hoops just to GET the drivers. Ubuntu, on the other hand, works out of the box, both from the live CD and from an install. In fact, every Linux distro live CD I've tried works out of the box. I skipped Vista, and my ethernet driver WORKED in that. If I can't get 7 to work I'll probably skip that and just go to Jaunty, which at least works.
Also I'm still not done fixing the damage the install DVD did to my bootloaders. Got grub back up but it can't properly chainload since Windows 7 destroyed all the pre-7 bootloaders I was chainloading to.
It did something weird to my DVD-ROM drive too, I can't read one of my DVD-RWs anymore. Worked fine before I booted into Windows 7 and copied files off of it, worked fine when I stuck it in another computer. Tried cleaning it, still doesn't work. WTF is that about.