For those interested in running Windows on an Intel-based Mac, this week brought two interesting announcements. First, in the ongoing battle of one-upmanship between Parallels and VMware, Parallels announced a new initiative to help developers package and distribute virtual appliances - prepackaged virtual machines containing a full operating system and applications, configured to perform specific tasks and ready to run without any setup. The Parallels Technology Network provides developer support and documentation; developers who submit virtual appliances that meet the requirements created by Parallels can be listed in the Parallels Virtual Appliances Directory, which is very much like VMware's Virtual Appliance Marketplace.

Meanwhile, Parallels Desktop and VMware Fusion now have another competitor: Innotek's VirtualBox, a free, open-source virtualization environment previously available only for Windows and Linux. Now available in its first public beta for Mac OS X, VirtualBox lets users of Intel-based Macs install and run numerous versions of Windows, DOS, and Linux, as well as other Unix-like operating systems. VirtualBox for OS X Hosts Beta 1 is a 16 MB download.