if you had a choice between NTL and Telewest, i'd go for telewest, they give you more for your money, with Telewest you can get
2MB Broadband got £14.99 for 12 months then £17.99 thereafter.
With NTL you can get
1MB Broadband for 3 months at £8.99 then £17.99 thereafter.
Check for yourself what you'd think is better:
www.telewest.co.uk
www.ntl.co.uk