What version of the MacOS is pre-installed on the Mac Pro?

The original Mac Pro first shipped with MacOS X 10.4.7 "Tiger" (Build 8K1079), the "Early 2008" Mac Pro first shipped with MacOS X 10.5.6 "Leopard" (Build 9B2117), and the current "Early 2009" Mac Pro ships with MacOS X 10.5.6 "Leopard" (9G3553).

Can the Mac Pro run all MacOS X applications written for PowerPC-based Macs?

A good percentage of MacOS X applications written for PowerPC-based systems can run on the Mac Pro, and other Intel-based Macs, using the "Rosetta Universal Binary Translator", but as one would expect, these applications will run more slowly than they would if they were "native" for Intel-based processors.

The always excellent MacInTouch provides a list of "Universal Binary" applications that will run natively on the Mac Pro and other Intel-based Macs. The same website also has a list of applications written for the PowerPC with readers opinions regarding their performance using "Rosetta". You may wish to consult these lists to ensure compatibility with any particular application of interest.

For more on Rosetta, please refer to "What is Rosetta? What does it support?" from the "Macintel" Q&A.

Can the Mac Pro run MacOS 9/Classic applications?

Apple provides no support for running MacOS 9 or the "Classic Environment" on Intel-based Macs. The Mac Pro relies on the "Rosetta Universal Binary Translator" to run software for MacOS X for PowerPC, and this emulator cannot run "MacOS 9/Classic" applications.

If you have a mission critical application that only runs in MacOS 9, you likely would be best served by maintaining an existing PowerPC-based Mac. However, you may also be interested in reading "Are there any third-party programs to run MacOS 9/Classic applications on Intel Macs?" from the MacOS 9/Classic Support Q&A.

Site sponsor Operator Headgap Systems specializes in refurbished, and often heavily upgraded, systems capable of booting in both MacOS X and MacOS 9. Site sponsor PowerMax also sells systems capable of running MacOS 9/Classic.

Can the Mac Pro run Windows? What drivers are required?

Yes. For those unfortunate ones condemned to use Windows, the Windows on Mac Q&A provides answers for just about everything you need to know about running Windows on the Mac Pro or any other Intel-based Mac.