After 4 years of extremely slow, but resonably good service dial up service from Demon.co.uk, I found it necesary to switch to BT to get broadband. Initially getting only 1 megabite download speed from our very rural exchange,which was an amazing speed increased, this increased to a potential 4.5 megabite download speed with the new BT home hub which was provided.
I subsequently decided to upgrade my own computer and my wife began to use my old model. We are both now connected to the hub via an ethernet connection and we now have 24/7 connection to the internet at excellent download speeds. While initially download speed tended to slow down at periods of high usage, we have found that, recently, BT are providing a high speed throughout the day approaching their promised high.
We both use their Broadband Talk facility which has become much more stable with the Home Hub set up.