Network interface (switches,Nic,connection)

[Craig]

I was trying to increase my limited knowlege in Networking.  I have considerd many different options for an 8 node cluster that I am building for my
school "Northeastern Universtiy".  I am a freshman but I decide to take on this project and need alittle assistance.  Of my many questions the first
is Gigabite ethernet or 100 mbp.  I understand the cost analysis but just what is the ture latency difference between the two.  Also layer-2 or
layer-3?  Unsure about the physical differences between the two.  Also I heard the term infinaband and im not sure what it refers to but it is
supposed to be the new standard in message passing.  Thanks