I've currently got a 20Mb/s cable connection, thanks to Virgin Media doubling all their speeds. Note that this connection only has 768kb/s upload, and is contended.

Most of the UK can get ADSL at 5Mb/s or so. Some places have ADSL2+, which can run at 24Mb/s if you're close enough to the exchange. Again, the upload on those is generally sub-1Mb/s, and there's usually a contention ratio of 50:1.

The main advantage of connections like SDSL and T1 is that the upload is faster, and there is no contention.

Edit: whoops, sorry about the thread drift. Might be an idea to split this discussion off into a separate thread.