i hate when a customer uses a single site for speed checks.....if you get a bad "hop" from one server to another, it can drastically affect "speed" results.
case in point:
i have a 6meg/512 connection & here are what i got.....
speedtest.net(the one everybody is using in this thread) : 2461/425
speakeasy.net : 5160/421
toast.net : 3333/314
dslreports.com : 1934/431
pcpitstop.com : 2070/438
those #s are like a shotgun blast all over the map....but i only pay $25/month for my home phone service & dsl