~$ sudo apt-get update && sudo apt-get install nvidia-glx
Get:1 http://security.ubuntu.com dapper-security Release.gpg [189B]
Hit http://security.ubuntu.com dapper-security Release
Hit http://security.ubuntu.com dapper-security/main Packages
Hit http://security.ubuntu.com dapper-security/main Sources
Fetched 1B in 1s (1B/s)
Reading package lists... Done
Reading package lists... Done
Building dependency tree... Done
Package nvidia-glx is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package nvidia-glx has no installation candidate