check your line here, need Bt phone # so use neighbours number to get estimate of expected performance.
http://www.prodigynet.co.uk/menu.php.../adsllinecheck
If it says 6500kbit I expect your line is fairly short and should expect good performance, if its below 6500kbit and/or one of the fixed speeds isnt green status then your line quality/length may reduce the level of service you can get.