With the mac pro, it pretty much is about OSX, well that and powerful reliability, but yes the hardware could be duplicated in a PC, but the Hackintosh solution isn't going to work for most people. Too risky.
Looking at a hands on demo video of the touchpad, I have to say Apple could take a few ques from this new WebOS implementation. Quite well done and solves some nagging ipad issues in an elegant way. Downside is the Summer availability and hopefully ipad 2 (April?) and an updated ios will compensate. nevertheless, well done HP I thought.