Is it worth upgrading a PowerMac 8600 with a G4 processor card, if your aim is to boost its speed in general, and, more specifically, to sharpen the performance of applications such as PhotoShop and Illustrator as well memory-intensive devices such as digital camcorders and cameras. I have received conflicting information regarding this issue. Apparently there is a diminishing return in the leap of a model such as the 8600 to G3 thru G4 status, and yet at the same time, I've read that it would increase the computer's power, especially in a program like PhotoShop (starting with version 5.5). Is it possible for a neophyte to installl a G4 processor, in particular, a Sonnett Crescendo/PCI G4 700 MHz upgrade card, without any hitches? Is it a matter of removing the old card and replacing it with the new one? Or is it more involved and necessary to hire a professional tech for the job? Also, I am considering a USB/Firewire combo card in order to save on PCI slots, will one of these work as effectively as having separate cards?