I'm finally going to replace my venerable mirror-door PowerMac G4 with a mac pro. This is a home machine that will primarily be used for hobbyist type stuff and light-weight web development. The heaviest-duty work it will be put to is the occasional use of Final Cut Express for video editing. As such, I'm thinking of "downgrading" to the quad-core option and saving myself $500 to spend on 3rd party memory and disks. The only reason I can think of to go the full 8 cores is to "future proof" the machine for as long as possible. As evidenced by my current system, I like to keep my desktops around for a long time before turning them over. So... if the quad system could be easily upgraded to the octo by simply adding a CPU, I'd definitely go with the quad knowing that I could add a CPU later should I feel the need for the extra cores. So anybody know if the quad system could be made into an octo just by dropping in a second quad at a later date?