No, sorry, it really doesn't.
The install space required by OSX is comparable to Windows 7. The basic hardware in a mac is the same in PCs. When you
buy a mac you
buy the ease and simplicity of OSX. I agree, OSX is an excellent OS. I love it on my laptop. The problem is mac's are generally quite a bit behind in video hardware, which is easy to upgrade in a PC, not so much in a mac. Not to mention video drivers for mac generally suck compared to the windows counterpart.
The same hardware running both OSX and Windows 7 will benchmark (realitively) comparably.
Anyways, don't wanna get into a mac vs pc flame war.