A pentium 4 3.2 gig with hyper threading on are just as fast or even faster. Mac benchmarked their systems against P4`s with hyperthreading off.
Also here in the Uk they`ve now stopped the G5 advert from being shown on tv because of false advertising.
http://www.theinquirer.net/?article=12601
http://www.theregister.co.uk/content/39/33909.html
64 bit systems are going to blow G5 out of the water when there fully compatible with software.