If anything, the way Speedtest.net is designed you get a higher result then you get. And I think he did mean Speedtest.net. I have gotten similar results. Speedtest, ironically enough, is not technically a "speed" test, but a capacity test. Meaning you would never be able to transfer 21Mb from site A to B. Rather, its the maxium capacity that the connection allows. Like I had told alot of people, network performance is probably one of the more complicating fields you can get into in IT. Next to maybe Data encryption. Here is a good page though on my site of choice though
http://www.myconnectionserver.com/whitepapers/measure_the_quality.html