You should definately get a shuttle. I got one just a few weeks ago and I am very happy with it. Just remember the following: You only get 1 pci slot you only get 2 3.5 inch drive bays (only 1 exposed) you only get 2 dimm slots you only get 1 5.25 inch drive bay If those things don't bother you, then you should be happy with it. I've got mine set up right now with a radeon 9800 pro, 4x dvd writer, p4 2.6C, and 512 mb ddr 400. If you are planning to watercool the video card, be careful which block you get. There is not much space between the agp slot and the case wall so you'll need a pretty low-profile cooler. I don't think a danger den maze4 gpu will fit, but don't quote me on that. Anyway, yeah the shuttle is a quality product that's very convenient for lans.
Well, to really recommend which one, we'll need to know a little more, how much you want to spend, etc. Do you prefer AMD over Intel? What kind of games will you be playing? All of these factor into which Shuttle will fit you best. I've never watercooled, but we have a few other BT members who have. Do a search for "watercooled shuttle" and you'll probably turn up some names so you can get ideas or PM the owner, to ask him how it's done.
AMD or Intel? It's really a matter of personal preference. I don't know if you can get an A64 shuttle or not, but that sounds like what you'd want. An acceptable alternative would be an intel 865 or 875 based shuttle. I have the 875 and its fast as hell. My shuttle psu is running just fine. They get damn hot but I have not had any power-related mishaps yet and its been running for a few weeks. On the psu subject, see if you can get ahold of Zapwizard. He built that amd/ati shuttle demo box so he should have a better answer on what the psu is capable of. Water cooling: Again, a matter of personal preference but in this situation I'd suggest a low-flow european type setup. I'm a bit biased as that's what I'm currently setting up, but I think it would suit your applicaiton well. The tubing is small diameter so it takes up less space. Also, you dont need a powerful pump for a european setup. Powerful pumps tend to be big and suck a lot of power. The pump in my low flow setup consumes only 5 watts! (Aqua computer aquastream) You can get even more compact pumps if you look around. I'll post some links if you want.
Get the shuttle SN95G5 with whatever processor you want, 1 gig (2x512) of low latency ram, an audigy 2zs and a 6800gt, that will set you for gamming, of course you will have to buy a hard drive and optical drive. The 240w psu will handle it, other people have done no problem
the 250 watt can support more than u think some people have 2 hard dirves cd drive and and x800xt. i would get a sn95g5 or one of the new p chasis when they come out and then a 6800gt and low latency ram and a 2zs audigy
i have a SS56G with P4 3.2ghz prescott (the 800mhz gig cache beast) 1gb 400mhz memory 200GB hdd sony dual layer dvd-rw ATI radeon 9800XT
A Shuttle PSU would handle an X800, as for the pump get yourself a relay to the mains, wouldn't like to try a 12V with such a small PSU. As for your watercooling go for something small like an Xice kit, check out this project log.
For a pump, try this: http://www.c-systems.ca/ Probably the smallest WC pump in existence. Edit: Not to mention it's 12VDC, and takes 3-6w.
