Really! Why do people still use those ancient Macs like 700-800 MHz G4s or even 450 Mhz ?
What are using those old Macs for? Playing music in iTunes? Surfing net? Cant think of another use... even disk storage was slow.
Playing music, surfing the net, checking email, IM, PIM functions? You mean, like, the stuff for which the vast majority of non-pro users actually use their computers?
For most purposes, there's not much real justification to buying a new, more expensive computer if the older one still works fine. The only reason I have three CD/C2D machines is that I do a massive amount of video/music file transcoding.