BT has been forced by the regulators to cut their prices on things like broadband by a big chunk by 1 Jan 2005.
This, of course, will trickle down to nearly all ISPs as they all require a BT line (except the cable companies).
They say there could be a little bit of a wait for the price wars to kick in but I wouldn't be surprised within the next few months to see reductions in price by quite a bit.
A number of the ISPs out there make you sign up with broadband for a 1 year contract so be aware of that.
I believe places like pipex.net and demon.net don't requite any contracts and are already quite cheap for the standard 512K offering. Wanadoo will come down as well although they've standardized at 1MB ADSL for some time now.
Prices will either come down on 512K connections or the ISPs will just whack up their bandwidth and charge the same price
To defend Tiscali, I've had them over a yer and have had no connection or billing problems, whatsoever.
Matt