Updating Graphics Drivers on BootCamp (Windows 7)

Hello! I've been trying to update my graphics drivers on my Windows partition on BootCamp, and I've been having some trouble. I have a late 2009 21.5 inch iMac running Lion and Windows 7 Home Premium 64 bit on BootCamp. I have an NVIDIA GeForce 9400. I went onto the NVIDIA website, went to the drivers section, and ran the automatic scan thing. It said that my current installed driver is 261.41 and that the latest update is version 306.97 WHQL. Clearly I'm very out of date and I would love to have my games run faster. I clicked the download button and downloaded the installer. I ran it, and it downloaded the files to CNVIDIA\DisplayDriver\306.97\Win8_WinVista_Win7_64\English. Then after that it "Checked System Compatibility". And right away said "NVIDIA Installer cannot continue. The graphics driver could not find compatible graphics hardware." I've tried multiple times and got the same thing each time. I have no idea what to do. I've never done this before and am basically an idiot when it comes to graphics drivers. So if anyone could please help, that would be great!

Thanks,
Natie

You may have downloaded the wrong driver. Your iMac needs the mobile driver set - yes, I know the iMac is not a notebook computer and is considered a desktop. However, iMacs are nothing more than large notebook Macs extended vertically.

We've run into this before with nVidia and AMD. The solution has been to download and install the mobile driver set. But you do need to take into consideration if your iMac really needs an updated driver. I'm assuming you think so because some games are not running fast enough?