Click the apple icon on the dock and click on "About this Mac" and your Mac will tell you the version number.
The Mac's operating system was originally known as the System Software. It later became known as Mac OS followed by a version number - Mac OS 7, Mac OS 8 etc. The current 10th version is known as Mac OS X.
Updating to the latest version of Mac OS X will provide you with the latest printer software. HP keeps a selection of software for various versions of Mac OS X. (See links below)
There is an older version of ClamXAV available (See links below) for Mac OS X 10.3 but as there are no viruses that attack Mac OS X anti virus software is superfluous.
McAfee is a software company that is well known for having created antivirus and internet security software for numerous years now. McAfee currently has a number of software available for the Mac OS.
Mac OS 9 software requires Mac OS 9, which was discontinued in 2002, to work. Early versions of Mac OS X came with Mac OS 9 included (referred to as Classic mode) which could be activated from System Preferences. The latest versions of Mac OS X no longer support Classic mode. It will depend upon your specific Mac model whether a version of Mac OS 9 can be persuaded to work.
No Mac OS version can be considered to be in the direct upgrade path, as Mac OS runs only on Macs, and is incompatible with all of the software of Windows 2000.
OS X is the all encompassing term for every version of Apple's OS 10 software from 10.1 to 10.6 (as of July 2010).Basically, Mac OS X is 10.3 Panther, but is also 10.1, 10.2, and every other version forth to 10.6.
It's possible that the Mac OS X version that is installed on your MacBook does not meet the minimum system requirements for iTunes 9. The minimum compatible version of Mac OS X is 10.4.11. If your MacBook has not been updated to at least that version, just run Software Update ( -> Software Update...) until you're running 10.4.11. To tell what version of Mac OS X you're running, go to  -> About This Mac.
Click on the Apple menu in the top left corner and select About This Mac. This will open a window which will give the version of Mac OS X you are running. From the Apple menu select Software Update... which will check if there are any updates available for the Mac.
iOS, a scaled down version of Mac OS X, is the operating system software
Selecting Software Update from the Apple menu will automatically provide you with the latest version of Mac OS X available for your system. To move up from one version of Mac OS X to the next (for example from 10.4 to 10.5) you need to purchase a copy of the new version.
Since there is no such version of Mac OS as in your question, I'm going to assume you mean Mac OS X 10.4, instead of 14.0. And no, Quick Books does not come with Mac OS. For a list of software included in the current Mac OS version, see the Apple Inc website at: "http://www.apple.com/macosx"