If you do a speed test & it shows your speed as 700 kbps, that'll give you roughly 75-80 KB/s. 8 bits = 1 byte.

Have a look through the sticky below, there are tips for optimising your LW's performance
Configuring LW for best performance

Keep in mind though, your download speed depends on your speed, host(s) speed, how many upload slots the host has open, how many hosts you're downloading from etc.
If you're really concerned about your download speed in general, dwnload a file from here & tell us what speed you get
http://www.magnetmix.com/video.shtml
(those should download pretty fast).