Well, thank you all for your replies.
I've made my decision (partly based on the opportunity), when Apple threw some refurb 3.0GHz Quads on the Apple Store last night. I had seen them before, but they go quick -- I knew if I wanted one I would have to grab one. I ended up springing for the Quad 3.0GHz (dual-processor) with 2GB of RAM and the ATI x1900 card. I think this is a good card all-round, and will be OK for gaming as well as driving a 23" and 30" Cinema display and doing video work.
The machine comes configured with 2GB (4x512MB) so I have a few options on upgrading the RAM, which I definitely plan to do. I could add four matched 2GB modules to give a total of 10GB in the system, which would be more than enough (this option would only cost me $314.99 via OWC, and it's probably the best way to go right now). I also plan to add a couple more hard drives for storage, maybe a 1TB and a 150GB 10,000rpm Raptor for performance, using this as a boot drive.
I don't really think I would need the 8-Core Mac right now, and I realize that it IS POSSIBLE to upgrade the processors to the x5365 (Clovertown) pair in the future, and this could be done for as little as $600....several websites (Anandtech and Hexus) have detailed this upgrade.
I decided on standard delivery, since last time I used the overnight option it ended up taking 6 days for me to receive my shipment. This way, if all goes well, I should receive my Mac Pro by Monday or Tuesday of next week.
For this machine, I paid exactly the same price that a current-generation 2.8GHz Quad Harpertown would run ($2299) but I'm getting a slightly better video card, and a dual-processor configuration (although I don't know if a DP 3.0GHz Quad is faster than a single 2.8 harper quadcore). I do realize the newer machines have more L2 Cache (12MB) and faster RAM bus (800MHz). All in all, I don't think I will be disappointed with my purchase at all. I have used one of these in a store and I was very pleased with the performance of the 3.0 quad. One thing I learned is that the RAM upgrade matters - immensely, so I plan to do that.
Just a question, lastly, if anyone can answer it -- would I be OK adding four 2GB modules to the unit, in matched pairs and upping to 10GB, or would it be better just to upgrade the whole machine to 16GB (all pairs the same size) as far as performance goes?
Thanks,
Ward