Computer Shelves

[Leonardo Magallon]

Greetings Beowulfers,

We are wondering about what shelves we should get for the extra 32 Duals we are adding to
our  already existing cluster.
I have been looking at all the shelves that are sold by companies that are specific for
computer systems.  These include places  for input/ouput peripherals and the like.  Since a
cluster does not use these peripherals on a per-computer basis, my question is: What would be
the difference between getting those metal shelves or getting the plastic regular tool
shelves one can get at SAMS or PriceClubs?
I won't be bolting them to anything to share a common ground (if at least one is needed.)
If I need metal shelves, then is grounding the shelf to some ground rod the recommended
method.  If I need a plastic shelf, is there any static electricity problems?

I am sure that there is a reason behind using metal shelves for computer systems because all
shelves I've seen in computer labs are made of metal.

Regards to all,

Leo Magallon