I'm in process of finishing a new DAW workstation myself. Each person will have different things they want out of it. My goal was minimal latancy, and the ability to mix together a TD-20, BFD2, and drum mic's. Cost was not an issue, but I did try to maximize my bang for the buck.
I went with an Alpha link AX for converters. SSL sound quality, 24 analog in/out, and about 100 samples round trip latancy.
MX4 for the MADI card. SSL EQ and compression comes along for the ride there. (Note, no DSP powered reverb)
The PC I purchased from PC Audio labs with the main drive solid state, and two terabyte drives, one for samples, and one for audio.
Preamps: Audient 008, RNP, and Black lion.
Word clock: Black lion
MIDI: Edirol UM3X
The cables with this setup required some work and planning with so many DB25 connections. I'm still in process of software setup.
Will end up using soundscape for Audio, and Sonar for MIDI and mixing automation. The only plug ins currently installed are BFD, Lexicon PCM, and Waves Durroughs meter. Note that software called Jbridge (20 bucks) is cool -that allows multiple 4 gig programs to fully use the 12 gigs of ram on this machine.
The Total system latancy is great. Sonar reports 1.3 Millsecond latancy at 96K, and I believe it. I have trigger sensing times (2.5ms) to compeat with for total live drum latancy, and the addition of this system compared to adding 1.3 ms to trigger sensing time has about the same total change to the drums feel.
One of the reasons I went with the MX4 card is the ability to time align each track. When I get down to nuts and bolts of blending together Mic's TD-20, and BFD-2 for a great sounding drum kit, I will be able to put each track at exactly the delay needed to line them up. A generally acceptaed latancy standard is that past 4.5ms total system latancy starts to eat away at the qulity of ones performance. I had to get a system this fast to get there because the triggers them selves take up over half of that time.
Minimal latancy was achieved by using MADI interfacing, and the fast AD/DA. The only AD/DA that faster is an RME QS that runs $3K/8 channels vs. the alpha link at $1.8k/24 channels. I also get the SSL sound, I dont know how the the QS line of RME sounds. Also worth a note is that I dont plan to use the ADAT IO of the Alpha link AX to avoid degraing the systems digital word clock stability. If you want a more complex digital setup, the SX version of the alph link costs more, but gives you good AES IO options.
I havea bout $12K into the system total, but I have preamps that don't detract anything, an SSL mixer, Leixon reverb, and it all fits in a 10 space rack case. When I feel like gettin to the mic's I will likly get seventh circle preamps, and Advanced Audio Mic's.