I saw this on slashdot and was floored by the coolness factor. This is definitely a DIY I would attempt if I had the time, energy, materials, and funds to pull i off.
This Maximum PC Article has all the information you need to create your own basic multi-touch surface computer. Obviously You could take that and modify it as you saw fit, perhaps a different setup for video, change the cabinets design, add ports or drive bays to the outside to make things interesting. Maybe even go as far as o add everything else you want.
Definitely worth reading, if you have the time and money certainly worth trying.