Test internal network speed

[UNCMo96]

I have a network with a bunch of variables that I want to speed test internally. Can anyone recommend a mac based product that's ideally free.

In case anyone's curious:
Actiontec fios router (soon to be the newer router with 802.11n) as main router
That is connected to a gigabit switch for an iMac, linux box, and my retina macbook when i wire it in.

Main floor has another fios router used as a MoCa to ethernet bridge and wireless access point. Unfortunately this one is g not n.

What i'm curious about is testing the ethernet over Moca vs. 802.11n for internal file transfers for my Roku to stream movies off my linux box and for my 4 squeezeboxes.