dell dimension 2400 video controller

I installed a clean version of windows 7 ultimate and everything seemed to run fine for a few weeks, then I started getting messages saying that the display driver has crashed and recovered.

So I went to the nvidia site and downloaded the drivers for my graphic card, but now sometimes the computer completely freezes up, making me manually power down and restart the computer again.

I uninstalled the nvidia drivers from their site, but I still get the freeze up nearly every day.

I also have the yellow exclamation mark under other devices video controller in device manager, and can't find a driver for it.

Is this an compatibility issue with the windows 7 os?

For better performance, which os should i use, xp or 7?

system specs:
dell dimension 2400
2.66 ghz, 2gb ram, nvidia geforce 6200

At a guess, the unknown graphics device is your onboard video, for the 845GV chipset. Intel has made no Win7 drivers for it:

Graphics — Older Intel® graphics controllers and Microsoft Windows 7* operating system

As regards your graphics card, it's on the supported products list for the latest drivers (275.33). I have no reason to believe that the drivers wouldn't support a PCI graphics card, which must be what you have, as the Dimension 2400 has no AGP or PCI Express graphics slot.

The machine is old (latest BIOS update in 2003), but it's above the minimum specs required to run Win7. I would have stayed with XP, if only to avoid spending money on a Win7 upgrade. (I have no access to student deals or other highly discoounted copies.)