Ok, if you're running Windows XP SP2, your bit torrents are going to mostly stink unless you override windows' TCP/IP limitation. There are a number of patches out there to do this, all of which are quasi-legit. Do a quick search on google for "LVLLORD".
Also, have you opened the listen port? You NEED to do that. If you have a firewall or a router, you HAVE to open up that port, or else nobody can contact you to say "hey, I have more pieces of this torrent for you".