An update from 11.10 to 12.04 failed because of a boot into black screen (Nvidia graphics card) after selecting normal boot in Grub (recovery console was available though).

I then wiped the whole partition (deleting all proprietary drivers) and tried a fresh install, but could not run the installation cd because it was booting straight into a black screen again.

Now I reinstalled 11.10 (and installed proprietary Nvidia driver version 173), and would like to ask 2 questions:

1 - Is there a proven method to fix this problem from the recovery console, so that I can safely try upgrading again (without much knowledge of Ubuntu)?

2 - Is there a website which I could check for updated Nvidia drivers packaged into the upgrade, so that I can safely upgrade without running into a black screen some time later on?