As another poster has said, your internet package probably has an advertised upload speed beside your download speed (which is what people are usually interested in). Since you will be sending pieces of your torrent accross the internet, I think this will be the main speed bottleneck you will face. This will obviously also be split between however many leechers download your torrent at once. But given the p2p nature of torrents, the number of people downloading ddirectly from you should be much smaller than the number of people downloading the torrent altogether.