I am going to replace the 10/100 NIC in my Unraid box with a GIG NIC tonight. What is the best way to compare before and after performance? Just copy a large file from another computer and time it?

Download and install bwm-ng... telnet in or go to your console afterloading it up, launch it (type bwm-ng) and hit "t" 3 times and you'll get a 30 second calculated average for your transfer.

 

http://www.gropp.org/?id=projects⊂=bwm-ng

iftop is a great program to monitor network speed.

 

package can be found here: http://www2.linuxpackages.net/packages/Slackware-12.0/Console/iftop/iftop-0.17-i486-1kan.tgz

Another great tool is TeraCopy.  It will tell you how fast the transfer is going.  Sorry, at work, no link.