Do you still have/pay for DSL service on the phoneline?
If there is DSL service on the line and if the 2Wire is configured properly I dont see why it wouldn't work. I guess you will either have to try it, or call your DSL provider to ask them if it will work.
What speed are you paying for?
What speed are you actually getting? - how are you determining the speed you are getting?
usually an older (3-4) router should be able to handle anything up to ~10MB/sec'ish.. so if you are paying for 20mb or higher service, and you arent getting that speed, an new router might help.. Since you are on DSL, i'm going to guess you arent paying for any more than a few MB/sec..
If you're paying for 5mb service and you're getting 3mb speeds, then I doubt a new modem would make a difference.. BUT before spending any $$ I would call AT&T and have them verify that everything on their end is correct.. all that said, a new router probably does not cost very much, and assuming AT&T will allow it, it probably wont hurt anything..
So - the answer is "it depends" ...
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