Is the new server completely up yet? Earlier today when I came to the site I got a message saying "If you can read this you are on the new testmy.net server" or something close to that.
There was also a members only testing server if I remember right.
My town's public schools use cable (Comcast) while the high school uses a T1. I think they use a T1 because they host the school's website on their own server.
It doesn't have anything to do with any part of Java at all. Most other test sites besides Testmy use very small (under 1024Kb) to test your speeds. Those tests aren't optimized for broadband.
It doesn't matter if AOL can reach 10Mbps, Comcast limits you to their speeds, either 4Mb/384Kb or 6Mb/768Kb. AOL is just an add-on to your service. I'd personally get rid of AOL and save that $14.95/mo or whatever the price is.