I have at&t dsl modem. Do I need another router?

First your speed will be governed by the service you subscribed to. This will be the absolute limit of overall speed. Only subscribing for a wider band service will fix that. You could try a new router, but it will have to replace the existing, you can NOT use 2 DSL routers on the same connection. But first scan every machine with the free download from a href="http://malwarebytes.org" rel="nofollow"http://malwarebytes.org/a as spyware on ONE machine can cause the whole network to slow down.