IMHO;;
I think its a matter of calculating the speeds you have presented in the excel sheet;

Bearing in mind Mbytes = Mbits x 8

Also, inorder to stretch and confirm the link; which I assume is shared; you may need to remove the clients and connect to the full pipe with one machine and download/watch clips from "Youtube",

Or get a premium account from "hotfile" or "rapidshare" etc which would open up full bandwidth when you try to download a movie.

Another test I have done is to watch a movie directly from "Megavideos" :  http://www.megavideo.com/?d=KPL6KB8K

(from: http://www.sidereel.com/The_Big_Bang_Theory/season-4 )

And use this program NetPerSec : http://download.cnet.com/NetPerSec/3000-18512_4-15690.html

and you can adjust NetPerSec to whether you want to measure in Mbits, Kbits, Mbytes, Kbytes on a live basis... That will tell you the true speed of your net as you stream or download.

You can also stream and&& download at the same time to see what is the highest speed you get by giving your Internet connection the heaviest load.

My thots.

w/regards
Stephen N.