Plusnet's usage policy is how "capping" should be done.
http://www.plus.net/features/usage_guide.shtml
Hopefully NTL have something similar in mind but somehow I doubt it.
ADSL is going to be head and shoulders above cable soon and with me getting better pings on an ADSL line to a server in the U.S. I use a lot and already having a BT line about half a mile from the exchange.NTL better give me and the half dozen friends I pimped NTL to when the 600k service first started a good reason to stay or at least no reason to leave. All including me are easily out of contract too.