On Tuesday, VMware unveiled its VMware Fusion Upgrade Program in an effort to get users of Parallels Desktop to switch over to VMware Fusion. VMware Fusion and Parallels Desktop are programs that let Mac users run the Windows operating system within Mac OS X on Intel Macs.

The VMware Upgrade Program lets users of any version of Parallels Desktop switch to VMware Fusion for $10. You can participate in the program through the Fusion Upgrade Promotion Website, where you'll have to fill out and submit a form. You must provide your Parallels Desktop for Mac serial key.

Users of VMware Fusion version 1 or 2 can also upgrade to version 3 for $10. A Fusion serial number from the version you are currently using must be provided.

Parallels recently unveiled the new Parallels Desktop 6 for Mac. The software today became available for purchase for $80. An upgrade from Parallels Desktop 5 is available for $50. Customers who bought Parallels Desktop 5 after August 15, 2010 can get an upgrade to the new version for free.