To install Virtualbox guest additions in operating systems that are installed into a Virtualbox VM, use these commands. This will get you up and running in no time.
deep-thought ~ # apt-get install virtualbox-guest-additions-iso
This will install the ISO image containing the guest additions. The file can be found in the /usr/share/virtualbox directory.
To just install the Virtualbox guest additions directly with Debian or Ubuntu/Mint, use this command.
jason@jason-desktop:~$ sudo apt-get install virtualbox-guest-dkms virtualbox-guest-utils virtualbox-guest-x11
This will install the guest additions. This is a very easy way to get up and running with a native resolution and better performance with a Virtualbox virtual machine.
deep-thought ~ # ls -hula /usr/share/virtualbox/ total 58M drwxr-xr-x 5 root root 4.0K Jun 8 21:37 . drwxr-xr-x 346 root root 12K Jun 8 20:49 .. drwxr-xr-x 2 root root 4.0K Jun 3 21:30 nls drwxr-xr-x 2 root root 4.0K Jun 3 21:30 rdesktop-vrdp-keymaps -rw-r--r-- 1 root root 958K Jun 3 21:30 rdesktop-vrdp.tar.gz drwxr-xr-x 3 root root 4.0K Jun 3 21:30 src -rwxr-xr-x 1 root root 1.5K Jun 6 19:21 VBoxCreateUSBNode.sh -rw-r--r-- 1 root root 57M Jun 3 21:30 VBoxGuestAdditions.iso -rwxr-xr-x 1 root root 4.1K Jun 6 20:58 VBoxSysInfo.sh -rwxr-xr-x 1 root root 4.3K Mar 6 01:25 x11config.pl
If you want to add the guest additions to a Windows Virtualbox session; just add the ISO as the CD drive and then install them within the guest operating system.