That's quite a tough question to answer, as you've got all sorts of constraints there... although remember that your cable has enough bandwidth in it to pump 250 or so digital television/radio channels through it - if you could set it up so that you (and only you) were only using the core network you'd have massive speeds - although fairly pointless as you'd hit a level where you were faster than the rest of the internet, so would have a load of bandwidth going spare
In any case, NTL will not provide you with a connection over 1.5meg, best not to toture yourself, with what could have been, eh?
Here's a related question for y'all though. I've heard a few times that a STB 150k connection will give you an effective 256k connection, as the STB needs at least this to provide interactive... running
This test suggested by Paulyoung666 (thanks mate) It looks like i'm only getting between 150-160k... this would suggest something is amiss, however I also realise that as i'm only paying for 150k it's a bit cheeky to start demanding the extra 100 or so k
In any case i'm watching to see what happens on August 1st.