topsi - sounds like you need some anti-virus (like the free version of AVG - see free.grisoft.com/ and keep looking for 'free' alongside download as they keep making it a less obvious link than their paid-for products!)
Also, Ad-Aware might sort out some of the junk which you can accidentally pick up. See www.savemybutt.com/ and look at the Downloads section (not my site but worth using)
Most ISPs have some FUP (Fair Use Policy) with limits on how much you can download.
I had a petition on the Number 10 (Downing Street) website but because of the election it is in limbo. It was aimed at getting higher speeds by using Fibre optic connections to the BT roadside cabinets {mostly deep green}.
If you have long term problems with low speeds (and neighbours with the same ISP don't) then there are guides and user discussion areas on www.ThinkBroadband.com
BT's estimate for my line was 5 Mbps but at present it is 250kbps (20 times slower)... a bit of a pain, but I had no dialtone for over 10 days so something wonky on the wires back to the exchange (and around 6 kilometers of wire doesn't help - losses are significant). If we had fibre, the distance for the copper would be under 300 feet not 19,000+ and I might get 30 to 40 Mbps...
Would like to get the government to fund rural areas first, to "level the playing field" for whole communities - schools, homes and small business - and it would allow teleworking, teleconferencing and cut traffic if it was done.