Alright fella, BT Vision contains the usual freeview stuff, but combines it with a PVR and IPTV service. This means that it is essentially like Sky+ in that you can record and pause TV etc directly onto the box, but also watch TV on demand and streamed TV content too, in a similar way to cable.
Now im not 100% sure on the costs of the IPTV stuff, but I believe the PVR is included in the cost of the broadband.
I know the IPTV aspect of things includes things like movies, music video's and Premiership footbal on demand, which BT has near-live content rights to something like 260 games per season.
It cold be worth a try, it may also hook up to your existing system, either as a standalone, or integrated system. If you dont have a PVR, you may fnd it useful for that feature alone, otherwise, you may feel the IPTV stuff isnt really something that you are interested in.
Have a gander at it, you may enjoy using it, it could well be used in addition to your current setup; after all, as it's included in the cost of your broadband package, its an extra little bonus and something extra on what you have now.