Checking ethernet connection speed


How can I check the connection speed that my NIC's communicating with my network (not maximum NIC speed)? I am new to MAC's and could not find this info in System Preferences\Network.

Thank you in advance for any help.
One easy way is to go to the Terminal and run this command:
ifconfig en0 [e n zero]
Look in the line that starts "Media:"
um. open activity monitor and click on Network in the tabs along the bottom.