If you just want to write with an Arabic script open System Preferences, select the Language and Text section, select the Input Sources tab and tick the Arabic boxes. To add Arabic to the whole system (for menus and open/save boxes etc) select the Language tab, click on the required language and drag it to the top of the list.
The main OS for Mac can be found on a Mac when it is switched on. The current main OS is called Mac OS X.
It will depend what you are trying to achieve and how you define better. If software is written to use Microsoft's Windows system and is not available for Apple's Mac OS then Windows would be better. If you are using a Mac made by Apple then the Mac OS would probably be more suitable but you can always switch to Windows on a Mac if needed. If you are looking for a cheaper, virus free, trouble free computing experience then Mac OS would be your choice.
Mac OS X 10.4 "Tiger" will run on a PowerPC G4/800MHz machine. It is the latest OS that Apple will support on that processor, however. At this writing (January 2010), Mac OS X 10.4.11 is the latest version of Tiger.
I have a Mac OS X but I know Mac OS is a computer made by the brand/company, Apple.
You cannot without erasing your hard drive and installing Mac OS 9 from scratch. Even then Mac OS 9 may not run on modern Mac hardware because Mac OS 9 needs the ROM chip to boot. Modern Mac OS X hardware uses EFI to boot the system instead of a ROM chip to boot. Mac OS X v10.0 - Mac OS X v10.4 support Mac OS 9 applications and can run them, you just need to install the Mac OS 9 compatibility program which can be found on the Mac OS X Install CD.
The second name of Mac OS X v10.4.5 is Mac OS X v10.4 Intel.Mac OS X 10.4 was known as Mac OS X Tiger.
The oldest mac OS is System 1
Mac OS Leopard
Mac OS X 10.4 (Tiger) needs to be purchased as it is not possible to update from Mac OS X 10.2.8
Unless the disc is damaged and so needs reformatting you can run the Mac OS installer over an existing Mac OS.
Mac OS X is an operating system released by Apple Inc. It is designed for Apple branded computers, which is why you will never see a Dell, or an HP computer run Mac OS X. There are only two important versions of Mac OS X, Mac OS X Server, and regular Mac OS X. Mac OS X server was designed for servers, while regular Mac OS X was designed for most computers. The current version of Mac OS X (10.6) is named Snow Leopard.
The Mac OS comes free with a Mac. New versions have a small charge.