Some suggestions: SANS has an excellent publication called "Securing Linux Step-by-Step." It's a little out-of-date in terms of distribution, but it has an excellent discussion of how to turn off all of the services you don't need, etc. Also you can use the walk-through from Bastille Linux as another check of vulnerabilities. Note that the above are pretty RedHat-centric. I don't have the foggiest idea what kind of hardware, etc. you should get, I'm afraid.