Try doing a couple speed tests. Remember LW shows speeds in kilobytes(KB/s) and ISP's usually advertise speeds in kilobits(kb/s).
1 byte = 8 bits.
http://www.t1shopper.com/tools/speedtest/ http://resources.zdnet.co.uk/speedtest/
You can also try d/loading a couple files from
http://www.magnetmix.com/audio2.shtml. That should give you a pretty good idea of the speeds you can expect.