[PLUG] Building a cluster of machines on a rack of common PCs

[tuxdna]

Hi,

I want to build a cluster of machines on a set of common PC boxes.
Specifically building a rack of let say 6 PC boxes, connecting them
over Ethernet, and ofcourse running Free and Open Source software.

Before I begin my research and investment, I would like to take
opinion from you about what all things I would need to take care of in
terms of:
 * how to build a rack to save space, with enough room for cooling?
 * selecting amount CPU, RAM, Network Switch, Power Supply
 * which brands to go for?
 * and how to optimize the cost?

Please note that I don't want to go for a ready-made solution from big
vendors like IBM, HP etc.

Thanks for your advice.

Best regards,
Saleem