Parallels also supports the connection of multiple hard drive images and the use of multiple disk images or physical drives for use as CD/DVD-ROMs, as well as the creation of virtual serial and parallel ports. All of these features make it a more customizable than Fusion to a user or an application's needs.

Both Parallels and Fusion offer limited choices for how virtual machines handle networking. Both products allow you to choose between using Network Address Translation to share your Mac's network connection or choosing bridged access to a specific network adapter. Parallels also offers a host-only option that allows the virtual machine to connect to your Mac and any other virtual machines as though they were connected via a network. But it does not allow actual network access.

Neither product supports connection to multiple network cards or networks at this time, though Parallels Desktop 2 promises support for up to five network cards.

USB device access

Both Parallels and Fusion support access to USB devices connected to a computer, though Parallels currently only supports USB 1.1. Parallels gives you the option of having devices be automatically detected and used by the virtual machine or to manually choose the devices that will be used. It appears that this is the how Fusion will ultimately function, but that the capability has not yet been implemented.