Chaging Routers

I am suffering very low speeds on my ADSL line (1218kps) and as I am in a rural area, more than 2 miles from my exchange, I do not expect great speeds, but would would think I should get between 2 and 4mps. My service provider has suggested a number of tests of which I have carried out all but the last one which is to change my router. Before I do this I need to know if I will have to re-input new passwords etc on all the equipment that uses the router, or whether the network will store the existing one. I am using a Belkin ADSL Wireless G router and have a Thompson Speed Touch (supplied by broadband provider) that I could swap over to see if it improved speeds.

Router is 3 feet away from phone socket and I have changed ADSL filter.

Any Thoughts?