Good stuff. I'm building a new one finally once Quad Q6600 drops to 200 bucks. True, quad is probly not needed for a trading comp but for the price why not?
Pulled these specs from an audio DAW building thread. Audio forums are probly a good place too look for trading comp specs as if anything audio is much more demanding.
GIGABYTE GA-P35-DS4 Rev. 2.0 LGA 775
Intel Core 2 Quad Q6600 Kentsfield 2.4GHz
CORSAIR CMPSU-550VX power supply
Corsair XMS2 4 gigs of ram
Cooler Master COSMOS case. check out this case, looks fantastic for keeping things cool without a headache.
Seagate Barracudas for HD but not sure how much space I want yet.
My trusty old m-audio delta 44 soundcard.
Not sure about video cards yet. I still just use an ancient dual head Matrox. Might just buy another one and see how that goes as far as a quad config.
Wouldn't even think of bother going to vista personally.
XP with these tweaks for maximum audio recording performance is pretty hard to top as far as effeciency
http://www.pcmus.com/TweakXP.htm
I was also look at some of those terrabyte external HDs. Anyone ever thought about using an old machine with an old monitor, leave it on 24/7 and just collect tick data all day? Something I need to look into once this new machine is built. May as well considering the price of good tick data vs the small increase on the electric bill.