Dual Xeons are great multitaskers, but overclocking mobos are limited and dang they are expensive. I think a regular P-4 system will work just fine and allow more of your budget to be spent on the audio stuff you'll need. I'll only cover the P-4 stuff since you are in the Intel CPU section, but if you are considering an AMD, then you will need to get the A64 3200+ or similar in order match the P-4. Price is close to the same. The P-4 is a little better at multitasking, encoding, and vid editing. The A64 is a tad better at some gaming benchmarks.
Choice of motherboard boils down to how many SATA harddrive channels you will need. If you can get by with 2 SATA channels and want to save some cash, then the Abit AI7 is a good feature rich overclocker. If you want the top of the line, then look at the Abit IC7 Max3. Asus has a similar mobo called the P4C800 Deluxe too. I'd recommend the 3.0C CPU since they are priced good and are great overclockers. They average 3.6 to 3.8 gig with good cooling. If you want good cooling that isn't noisy, check out the Zalman 7000A heatsink.
For the other stuff: You have two options with RAM, PC3200 which will work good at the 5:4 memory ratio or PC4000 at the 1:1 ratio if you want the most memory bandwidth. Get a couple large capacity SATA harddrives like Maxtor, Hitachi, or Western Digital. For the vid card I need more info. Will this computer ever be used to play 3D games? That will influence what vid card to choose. For sound card you will need a professional card and I don't have that experience. You better check out the sound system section for recommendations in that department.