Well I live in a house with 5 other people, we have an 8 meg line (with a 1/2 a meg upload), we are upgrading to 16 meg soon. However if we are all run P2P programs at once it would be the death of our Internet connection for anyone who wanted to use it to browse the web or play MMORPGs. So we have a server in the front room which has both Azureus and eMule Plus on it all the time, which we can either go downstairs and access or use the network and access their web interfaces.
We have found with careful monitoring of how many connections these programs can open we don't have a problem with Internet slow downs.