I've got singtech lap top, model-w251hp, with nvidia gt520m 1GB graphic.
I installed Ubuntu 12.10 yesterday and try to update. But I can't find NVidia driver in Settings/Software Sources/Additional Driver/.
So, I typed the following command that I found in some forum:
sudo apt-get install nvidia-current nvidia-settings
After the reboot, my desktop has gone.
No side bar. No keyboard icon or time on top right corner.
Everything except the desktop background has gone. But, I can still press Ctrl+Alt+t and can open terminal and type firefox for browser.