It's not the programs that are illegal. It is the files you choose to download from other people that may breach copyright rules or laws (remember, Gnutella network does NOT have a central server, you are sharing with other people like yourself.) So careful choice of what you download & share back.

If your ISP has sent you such an email, then you are probably breaching their Fair Use Policy. You should go to their site & read through it & check what conditions they have set.

ISP's can sometimes be a little hypocritical, allowing downloading copyright music & movies from sites you pay for downloading from such as iTunes, etc. (Not to mention such movies can often be video taped off TV. lol)

Options: Off-hand thoughts: (a) do not download copyright movies for a time. And if do so in future, keep it to a minimum. (b) look for another ISP which does not have such restrictive fair use policies. (c) do not download copyright movies.

Others may have advice to add for you.