I have the same problem, live in the sticks with a long line, about 8k. I found that I got a reasonable result using a face plate (already mentioned) and a Thomson SpeedTouch router, a 585 I think.
I did a bunch of research when trying to get the broadband working and found that this router was being used in Oz with some success, obviously long lines there!
I think someone already mentioned some router chipsets are better than others. I think (might of been binned) I have the SpeedTouch modem (not router) at home which I used initially to test the chipset. If you want it I can send, but not home until mid March.
We (the village) are going from probably one of the slowest to one of the fastest places in the country later this year with a wirless link to a fibre optic backhaul into the BT main network and some 20Mbs+ DSL, courtesy of some grant funding.