Wow! Thanks for all the responses guys.
...ok, i'll try and answer everyone. The booster I have is next to the freeview box, it plugs into the mains. The aerial in the loft doesn't have an amplifier, and although its an outdoor aerial, its pretty small. (argos page 406, item 2). Judging by the many other types of aerials that are available, I'm thinking that I need a better one. But I have no idea where to start. From the little knowledge i've gathered i'm thinking that I need a High Gain, wide-band aerial with built in amplifier. Would that be the best way to go?