I ahve a cable 512kbs connection limited to 250Mo of upload. I ahve noticed that although no uploads of files from my disc are taking place and although I have disactivated file transfers and web exchange from my mac, I am still consuming a very high debit of upload. Can someone explain why? Logically if I have disabled file transfer from my Mac and from Limewire, and there are no files in the shared files file, there should be no upload. This does not seem to be the case with me.

Please explain how you turned off your upload capability in LimeWire.
:-)

Options : upload bandwidth and nr of simultaneous uploaded files = o.
Even if this is useless, I still do not see why I have such a heavy upload rate when no one seems to be sharing my files since I have none in the shared files folder and all the file sharing options of my Mac are disabled.

When you are connected to the Gnutella network, searches are going into and out of your computer. A lot of traffic comes downstream to you. LimeWire will pass on the search requests from others and will also send out results for search requests that match files in your library. This Gnutella traffics can easily consume all of you bandwidth (up and down) if you have lots of connections. Dial-up users can't usuall handle more than 3 at a time. Soooooo.... even though you have disabled file sharing, you are still an active member in Gnutella network activity, and you will therefore use a lot of upload bandwidth to participate in the network.
:-)