About the only thing you could do is look for T1 or T3 hosts with 4 star ratings and their speed rating displayed in green (which apparently means that the transfer speed that is displayed in their search result has been verified as being relatively accurate). But even that won't guarantee that you'll get higher speeds... mostly for the reasons I stated in my first reply.

However, what I like to do is start downloading a file from one source and then perform subsequent searches every few minutes for the same file. If LimeWire finds another host with a free upload slot, it then starts in with multi-host downloading. Even if the second source is downloading at only 5KB/s also, it still beats downloading from a single source at 5KB/s. Sometimes I'll get lucky and find a second source that I can download at 40 or 50KB/s. Most of the files I download are quite large (anywhere from 50MB to 750MB... averaging around 150MB) so every little bit counts.