512 kbps = kpbs/8 - overhead = real speed in Kilo Bytes per second

The downld speed is usually dependent upon your sources. So if you can find more sources for that particular file, with any luck you'll get faster speeds. (Unless your ISP has anti-p2p techniques such as bandwidth shaping when they detect p2p programs being used.)

Test your LW speed out with a magnet link from here http://www.magnetmix.com/video.shtml