Networking performance

[Deric Kwok <deric.kwok2000 () gmail com>]

Hi

I would like to ask your professional experience about switch throughput

I have Gig Switchs eg: H P3400 /3500, cisco c4 948../ dlink
In their spec, they said that it can handles Gig
So far, I couldn't see their ports are used up over 200M in mrtg graph
when I try to transfer 3G size files to files between computers

ls there any limitation in those switchs?
or I have to do configuration eg: put it full duplex instead of auto

Thank you for your help