it's technically faster. You can't really compare the two in the same since. So, a dual 2gig G5...4gig, is like 8gig pc...kind of..
so the dual 2gig pc, is like 4.... but really that isn't all that acurate...the dual 2 G5 is definenlty faster than the dual 2gig pc....but when you get the fastest dual pc..things get much trickier.
Like my powerbook 1ghz G4....it's about equivelent to a 2ghz pc....though really..it's faster at some things....the same with others...and probably slower at some things...
they're built on a totally different type of architecture...but this is information I've heard..basically.....take any mac processor, double it, and you get it's pc counter part.....at least close to.