I got the components and assembled it over the last couple of nights. Here are notes for other brave folks doing this:
* Pricing. Make sure you get good pricing on the Athlon 64. These prices seem to be changing weekly. There is good availability if you go to http://pricegrabber.com, but for instance the Athlon 64 3200+ on newegg.com was at $420, then$405, then at a bundle price of $350 and is now$300.
* Shuttle Assembly. The assembly is harder because the CD/DVD driver holder doesn't come out. Otherwise no more complicated than Pentium 4 or Athlon XP installation.
* Corsair 2GB memory is *slow*. Only glitch here is that is actually CL3 memory, so not as fast as the 1GB stuff. The specifications for the memory is 3-4-4-8, but the SPD is 3-3-3-8 which seems stable even overclocked on this board. I'd recommend the 1GB C2 version of Kingston HyperX or Corsair Twinx. They are much faster.
* X-bit labs - Articles - Socket754 Platform: Overclocking (page 39). Going to try a little overclocking. Basically the limitations are that the VIA K8KT800 doesn't really allow this but the nForce Pro 150 chipset does. The 3200+ runs natively at 2GHz and X-bit test show that they could get up to 2.3GHz and 2.15GHz with the Shuttle motherboard with the stock fan and overvoltage from 1.5V to 1.65V. I've gotten mine to over clock to 2.15GHz at 1.5V no problem. As a comparison, the new 3400+ is a 2.2GHz part.
* "Shuttle on Quiet'n'Cool":http://www.shuttle.com/share/fae/hq/faq/sff/qa/XPC%20Barebone%20SN85G4.pdf. Read the FAQ from Shuttle. Its obscure, but follow the "X-bit":http://www.xbitlabs.com/articles/cpu/display/athlon64-3200_4.html instructions. You need an Athlon CPU with an 'AS' suffix, you need to update your BIOS on your SN85G4 to "S015":http://www.shuttle.com/hq/support/download/dwn2.asp?model=SN85G4. basically, you can implement quiet and cool on this box by first updating Windows XP with all the latest hot fixes. Then, you can go to AMD and install their latest processor "driver":http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_871. Finally, you go to the control panel and turn on power management. Now the box will manage both the CPU clock (going between 800MHz and 2.0GHz) and the voltage (going from 1.29 to 1.5V) based on CPU utilization. This lowers power consumption from 35W up to the 90Watt maximum. Very cool. You can see this by running CPU-Z and it show dynamically what is happening. Kind of neat.
* "nVidia":http://www.shuttle.com/hq/support/download/dwn2.asp?model=SN85G4. As usual, the you need the latest chipset drivers. One bummer is that the Hypertransport bus on the SN85G4 is only running at 600MHz not 800MHz. Watch out for a Shuttle that goes to the newer nForce3 250 (the SN85G4 today has the nForce3 150). These drivers are right now 3.43, but check to see when newer ones come.
* "ATI":http://www.ati.com/support/driver.html. These video drivers are *always* changing. Go get the latest ones for the best performance.
So after all that, how does this machine do? Well, here are some benchmarks: