If you want to do heavy P2Ping, don't bother with the big name ISPs here in the UK. Pipex is one of the bad ones too

EDIT: Apparently Bulldog is part of Pipex anyway, so you're not really doing any change there
If I get a new connection or move house, I'll probably go with a smaller ISP - if you're willing to pay that little bit more and know roughly what exactly your usage patterns are like or able to control them a bit, the quality offered seems to be much better. I've currently got my eyes on
adsl24 and
KeConnect.
Be might be another to try if you're in/near London, though it's harder to tell their usage policies from their site. The main problem I have with most ISPs is their Fair Usage policy, whilst understandable why it's there, is far too vague on what sort of usage is considered bad.
thinkbroadband is a good place to check out and compare ISPs here
