Get a 3D printer, vinyl cutter, poster printer, and other fabrication tools so that the computers can be applied to a wider domain. Grab some arduinos and electronics to interface computers with sensors and motors. Consider getting some easily hackable gadgets like kinects, wii-motes, webcams. A couple DSLRs w/ fluorescent light kits & green screen?

I'd include ubuntu, OS X, and windows in your network if you can; if you're creating a budget of some sort, don't forget creative software costs (Visual Studio, Adobe Suite, Autodesk).

Make sure you will be able to grant administrator access without compromising the lab (you can use something like windows steady state, but I'd also keep backup images at a clean state). A local storage server with redundancy is a good idea to keep system images and other work safe.

Go for the skylights and vegetation; there are a lot of shade loving vines and plants that thrive with only a little light.

Check out this project from Tokyo Hackerspace:
http://tokyohackerspace.org/en/project/tokyo-hackerspace-netrad-geiger-shield

"This is the project page for the Tokyo Hackerspace/RDTN Geiger project. This is an Arduino-based geiger counter shield that makes it easy to upload data to the internet and also interchange tubes. Since it's open source and Arduino-based, its also easy to hack this to other interesting applications."