The Intel-based Mac Pro is a nice way to go. You'll come to appreciate using Macs for photography. There are good reasons why so many pro photographers prefer them.
Keep in mind that you don't need more than 3 GB of RAM for OS X right now (if you're thinking of maxxing out the memory). Anything else would be wasted until a more capable 64-bit version of the OS becomes available...And don't sweat the timing of the next Photoshop release, which is soon. It will take you a month or two to get everything up and running smoothly anyway. You can use that time to familiarize yourself with the Mac OS. By that time, the new version of Photoshop should be be out...
"...15 Maxtor 500Gb (Firewire400/USB2) hard drives with my 1000 DVD collection and simply want to play them on my Sony Ruby..."
15 500GB HDs? Purchasing all the original movie DVD's? Wow. As a professional photographer myself, I salute you -- and your (apparent) respect for copyright law. Don't apologize for these purchases. If you have children, it teaches a strong ethics lesson about intellectual property and the rights of others. On behalf of all creative artists, thanks.
Back to the movies, are you running your drives as mirrored RAID arrays to keep all those ripped movies backed up? Or do you simply rely on the original DVD as the backup? Have you ever considered Apple's Xserve RAID?
It is a serious server product that is gaining much respect in small business and recently, even corporate IT managers have started to take Apple's revamped server business seriously. A pro photographer friend of mine started with a storage system like yours (though Mac-based) and kept adding FireWire drives until he had a bewildering rats nest of dasiy-chained drives and cables -- and serious system maintenance issues. Finally, he landed a couple of nice national advertising accounts and graduated to an Xserve RAID system and loves it. While expensive to justify for the home, if you've been successful in life and have the resources to do things right, it may be the way to go someday...The 1U rackmount server has a quad-core 64-bit Intel Xeon processor and starts at about $3000. It will house up to 2.25TB of storage, has two PCI Express slots, dual onboard Gigabit Ethernet, and a combo drive. The RAID box that can be added has fourteen drive bays that hold up to 7TB of storage (calculated with 500 GB drives).
The Xserve RAID greatly simplifies backup and drive maintenance/replacement, and gives you serious media streaming, Web/LAN serving and desktop management. It would be terrific for your raw and finished Photoshop files as well as movies. Someday, I hope Apple will produce a more affordable SOHO (and home theater) server system based on this very nice technology.http://www.apple.com/xserve/http://www.apple.com/xserve/raid/http://store.apple.com/1-800-MY-APPL...clm=XserveRAID