depends on your ISP, a lot of the LLU (Local Loop Unbundled - means that your net connection is connected to your providers equipment in the exchange rather than to BTs gear and then to your ISP further up the line)ISPs (sky, Be* etc ) dont throttle connections unless your REALLY taking the mick (sky dont at all now as they have enough bandwidth to handle their network usage)
My opinion on UK ISPs
Tiscali are dreadful and I'm glad they are going / gone bust
BT are a bunch of nasty spies and have useless tech support somewhere in SE Asia (unless you use their overpriced business broadband where you get to speak to some moron in Newcastle/Dundee/Insert other former industrial heartland with high unemployment) Google "Phorm" for more informationAOL : again overpriced and crappy
Talk talk : they are cheap...no other redeeming features
Sky: Trying to improve, Level 1 tech support almost can do their job and their equipment usually now just works, speeds good and on LLU CHEAP
UKOnline (owned by SKY but diff purpose) : relatively expensive compared to other LLU services but decent tech support, only get hassle if you massively impinge on other users connection speeds, I hammer my connection periodically and thus far have no letters.
Be* /O2 : Have no experience with as they have yet to enable my exchange despite marking it for an upgrade, speeds again good and prices fair (especially on O2 if you have an O2 mobile

)
Entanet: sell their service via resellers, speed good, Enta tech support great (business quality tech support, polite, knowledgeable and very helpful)
Really you get what you pay for, I pay around £25 a month, but for that I get Service Level Agreement if there is an outage beyond a certain time, 24/7 tech support and lower contention (share space with less people)
Connection speeds can be improved a lot by using better quality cabling for extension wiring.
Server speeds are becoming less and less of an issue, a few minority sites (I.E. local newspapers) are still speed limited, but CNN, BBC, Msoft, Canonical, Redhat, Apple, Cnet, 1and1 and many other sites have very fast internet connectivity with a lot of redundancy. Also the fibre links between britain and the US have been improved a lot in recent years, speeds are pretty consistent between UK and american sites I have found during testing.
Though Britain on the whole has it easy compared to North America, a lot of places there struggle to get dial up due to massively long lines (one place I was had a line length of over 20Km as the exchange was in the nearest town (about 20km away) Therefore no hope of ADSL / Cable and barely got 33.6Kbps on dialup; less if the weather was bad )
I happen to work in Newcastle for BT mate, id appreciate it if ya kept opinions like that to yaself, dont tar us all with the same brush, were not all bad, you also make it sound like we live in a slum or summit, get a grip, the team i work with arent morons at all. I cant comment on the business broadband team though, but ive had dealings with them and they have always been in Dundee.
On another note, i can vouch for Be broadband. Been with them since April and they are spot on, the speeds are fine, ive never been throttled even though im a heavy downloader. Ive also found that customer service is great, there is no need to ring them as you can raise your own trouble ticket on line and you only close it when you are happy with the outcome, the response time is good for that aswell.
You can also set your own speed profile on your line now depending on how you use your connection, so there are settings for gamers or stability etc, this can be done from your member page, it just changes settings like your DSLAM SNR and interleaving but it happens immediately. :)