Throttled or not, running torrents at the same time as anything else (even simple browsing) causes a massive slowdown, not necessarily NTL's fault.
They do give torrent traffic low priority during peak times (that is what the traffic shaping/throttling is, I thought) but browsing should be given higher priority so it shouldn't be slowed down. This is what I've read, anyway.
Limiting your upload speed and download speeds in your torrent client should make a big difference to browsing and anything else you do at the same time I think. If it's possible though I think the easiest thing is just to run torrents overnight.
In the end, I think you'll find it hard to find an ISP now that doesn't either cap monthly bandwidth or throttle. I personally prefer to have unlimited but throttled bandwidth than having a cap at 30 or even 10 or 5 GB per month. But then that's probably because I don't use bittorrent much
