There aren't many actual option sin the UK, it really boils down to 3:
1 - Cable companies (eg virgin) who have their own fiber cables and equipment and can use whatever speed equipment they feel like buying
2 - ADSL broadband from BT or from one of their umpteen resellers. Almost all ADSL is actually BT underneath.
3 - An ISP who has used the Local Loop Unbundling (LLU) law to put their own equipment in the telephone exchange thus they can buy whatever speed equipment they want. These are rare, the mains ones are Easynet (also known as UKOnline and Sky), and Be. There are a couple of others too but that's about it.
If you use a company from option 1 you can get all sorts of speeds (eg 20Mbps), if you use a company from option 2 you will most likely get 8Mbps max. If you use a company from option 3 you will either get 16 or 24Mbps max. Problem is that not many exchanges have had non Bt equipment fitted as of course it costs money. So Easynet, Eky and Be start out upgrading the busiest exchanges first, eg ones in London and/or other cities.
This is how Sky can offer 16Mps (or whatever it is) to certain customers (one3s on exchanges that have their equipment in) and even offer basic broadband for free to some customers (again because their equipment is in the exchange, paid for and they don't have to pay BT anything).
You'll be especially sick to know that I also get £4 a month off my bill for being one of the original testers so I just pay the £18 and get the static ip for free...
