Growl adds a pane to the Other section of the System Preferences from which it can be configured to your needs.
You cannot run OS X on a windows machine.
The name of the computer can be changed in the Mac OS X System Preferences' Sharing section.
Signatures for the Mac OS X Mail application are changed from the Signatures section of Mail's Preferences.
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.
Mac OS X is pronounced Mac OS Ten. It follows on from Mac OS 9 which was the last version of what is now known as the classic Mac OS and it saw the introduction of the new UNIX based OS so the Roman numeral X was adopted to mark the change.
I have a Mac OS X but I know Mac OS is a computer made by the brand/company, Apple.
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.
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 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.