Don't forget the forums over at
adslguide if you want to get an idea of how Sky are performing. As you've touched on Kronas, it does depend on a few factors, as to what speed you can actually achieve. Are you already an adsl user, or are you moving from NTL ?
There is a good checker available from
here, if you already have an adsl line, and want to check what sort of speed your line can support.