"Faster"?
A nitro-burning funnycar is certainly "faster" than a family sedan or even a high-performance street-legal sportscar, but I wouldn't wanna have to rely on one to commute to work/school or go shopping, nevermind chauffeuring a load of friends or family around town...
Unless yr doin' the computing equivalent of dragstrip runs (i.e., heavy-duty number crunching or pro-level media manipulation), the Mac will be just as usably fast as the PC, perhaps moreso in terms of actually accomplishing real-world objectives; the Mac GUI is simply designed to be much more intuitive and, thus, efficient -- it "gets outta your way" and lets you get on with actually using the computer to do things instead of wasting time (and idle clock cycles %^) whilst troubleshooting and jumping thru hoops to figure out how to make it do what you want, followed by more hoops to actually do that and see if it works as expected... "It just works" has become a Mac cliche by now, and for good reason -- it's the simple truth.
As for longevity, I've still got my PowerMacintosh 7200/75 (as in, a whopping 75MHz -- w00t, baby! %^), which is now ~8 years old, still operatng perfectly, and still perfectly usable for general-purpose and light production use (email, web, school-/office-type stuff, jukebox), and I've only ever upgraded it by adding RAM, VRAM, a Cache stick, and a second, bigger drive (note that all the original eqpt. is still in place, just augmented with newer additions).
Don't s'pose youv'e seen many, oh, Pentium 90s around lately that are still in good shape with OEM equipment, and which are still regularly usable? Rest assured, you can and perhaps will keep using your Mac long after your PC-using friends will have chucked and replaced a PC or two or three...
