The specs IQ listed are pretty on point.
Only mods I would make would be Seagate hard drives (very quiet) and Antec power supplies (again, very quiet).
You also want a case that stays very cool but does not let a lot of noise out.
Here's a super, super quiet CPU fan: http://www.newegg.com/app/ViewProduc...115&depa=1
If you're going with Corsair ram (which I personally love) go with the XMS series, CAS2. It's verrry fast, and not much more than the regular.
Personally at this stage in the game though, go with whatever Athlon64 chip you can afford. You don't need to go for the socket 939 ones, but definetly the 754 ones will kick ass over the XP series, and do not cost much more at all. WELL worth it. Even if there isn't much 64bit support yet, they run 32bit stuff faster than the native 32bit processors do.

Just remember.. the less noise in your case and in your environment the more accurate your sound will be. ;)