Finally, the answer to my 1GB problems!
So, after 5 months of getting anywhere from 300-500mb on a 1GB there is a solution. I had been told it was my brand new SB8200 modem or my cables were bad. I finally had a 2nd tech visit and got the answer.. bad node. The node is bad and only sending 3.0 signals and not 3.1 which it should be. He showed me a pic of the speed test scan and it looked exactly like my speed test. It would start high and drop off, which is where the 3.1 channels are supposed to be. The bad part is, after reading posts here I tried to tell the 20+ people I talked to in chat and the 1st line tech that came out. I was told they would look at the node the 1st time, which they didn't. So, it might not be your SB8200 after all.