Good advice Nanaki
Other things can help get you slightly closer to your estimated connection speed, such as good quality ADSL filter(s), making sure your router is plugged into the main BT phone point in the house (eg no extensions, try plugging in direct into the BT test socket), check a speed test on another PC/laptop plugged into your router to rule out software/hardware problems, and the dreaded spyware.
Mods shouldn't this thread be moved to off topic? Sorry guys, but I hate reading/posting about work when I want to breath fresh V-power vapours......