No, it's not. But Vista has similat to OS X interface, at this point it was derived from OS X.
All Macs shipped today come pre installed with Mac OS X 10.5.6 Leopard, and iLife 2009. In addition you have the option to order some other software (Such as iWork) pre installed for an extra cost.
There is no print screen key for Macs, however, there are several key combinations for taking screenshots based on what you want to do with the screenshot.
I personally use Cmd+Shift+4, and select what I wish to take a picture of, or if i want to take a picture of a window, I press space. This will save the screenshot on your desktop.
However there are several more available, see related
An unpatched copy of Mac OS X will not install on a standard PC. There do exist cracked versions of Mac OS X that will allow you to install it on a select variety of PCs. WikiAnswers does not provide any information on how to patch OS X, nor any information on how to install it on a non-Apple branded computer.
Amazon.com is the best place to buy halo Combat evolved