Yes, your isp might be filtering/shaping your bandwidth. Some isp's are p2p unfriendly & cap the speeds for those who downld large amounts of data/use lots of bandwidth.

Download a sample magnet link from here: http://www.magnetmix.com/video.shtml
Tell us what speeds you get. And is that anything like your normal internet speed? You can do a normal speed test using one of the nearest test sites from here http://www.t1shopper.com/tools/speedtest/
But if they quote the speed in kbps (kilo bits/sec), then divide it by 8 to find the equivalent in KB/s (Kilo Bytes/sec.) LW shows speeds in KB/s not kbps.