James Bannan24 December 2008, 12:12 AM
How to run Windows Vista inside Mac OS X, without paying for VMware or Parallels. Our step-by-step tutorial will give you all the information you need!
Page 5 - Step 5 - Install Guest Additions

Most virtualization solutions offer a software package which can be installed on guest machines which provides better access to the host hardware and other resources like shared folders, clipboard, file copying and so on.
Once the Windows Vista VM has been installed and has rebooted log into the desktop. Then, press the host key to release the cursor, then select the Devices menu and then "Install Guest Additions". This mounts the additions image into the VM.

The additions media will autorun - launch the setup and click past the UAC prompt. Click Next, the accept the License Agreement and click Next again. Accept the default install location and click Install.
Setup will continue, and the package will install a number of drivers which offer better integration with the host's resources and improved guest performance. These drivers are not signed by Microsoft, so you'll get a warning popup message during installation. Click "Install" on all the popups, then reboot to complete the install.
When the system restarts you'll be able to move the cursor between guest and host without having to use the host key, and there will be an icon in the system tray indicating that the additions are active. Installing the additions also gives you extra functionality between guest and host, which we'll look at in the next step.