Well, I got AT&T tech help and they determined that my DSL download speed was way below target! Use
http://reviews.cnet.com/internet-speed-test/ and/or
http://www.speedtest.net/ to see if your Internet download speed meets the requirements for the purpose. See
http://support.apple.com/kb/HT1577 for download speeds required for different purposes. They had me replace the filters (the little 3-inch long matchbook-size boxes with 2 jacks and a 4 inch long phone line pigtail to plug into your wall phone jack) on my phone/DSL wall jacks. Be sure that you plug the phone into the phone jack and the DSL line into the DSL jack - they are NOT THE SAME! The filters that I had on before were either degraded or not up-to-date. Be sure that when you replace your modem (or router?) that you replace the filter with the new filter that presumably was sent to you with the modem/router. We were able to watch our first streaming Netflix move on Apple TV now that we have 2.55 Mb/sec download speed. 😉 Thanks AT&T and Apple tech support!
By the way, I was checking to see if I could get a higher speed DSL service. It turns out that my neighborhood in Berkeley, CA, is too far from the main Berkeley terminus of the fiber optic line to have a service higher than 3 Mb/sec. Maybe one day they will install a fiber optic line closer to my neighborhood, but right now I have the fastest service that is available here. One day maybe U-verse (with very high download speeds of up-to-6, -12, 18 or -18 Mb/sec download speeds) will come to my neighborhood. Fergunnessake I live a few blocks from the University of California at Berkeley and just a short hop up the freeway from bloomin' Silicon Valley! What gives? At any rate my download speed has almost quadrupled to 2.55 Mb/sec by changing the filters! So I'm pretty happy. 😉