AMD is generally slightly better than Intel for gaming (and much cheaper) while Intel dominates the media creation, decoding, encoding, etc. Higher clock speed = faster media creation.
I'd definitely go Socket 939 clown, but I honestly don't think there are any 939 motherboards out there yet. If you want to wait, there will be some soon, and it would definitely be a better choice. That would allow for big-time future upgrades. Socket 754 won't last as long as socket 939. Whatever you do, don't buy a damned socket 940 motherboard.
I'm not sure how loud the Raptor drives are...they are 10,000 RPM, and that's sure to be pretty noisy. Maybe a TFP member can tell us how loud they are compared to regular IDE hard drives?
One question, though: how is your 9800 Pro starting to show it's age?? That's still a top of the line videocard, man! The only thing in your current setup that's showing it's age is the Athlon XP 2000+. With a new processor + new RAM, you could have a top of the line gaming machine with a small fraction of the price.
-Lasereth