You can only download a file as fast as someone else can upload it. If I have one person downloading a file that I own, they can often download it quickly. If, however, I have 20 people downloading files that I own, each of them will only get 2-3 kB/s. Multiply that by the 10 hosts that you max out at, and you get about 30 kB/s.
By the way, I have cable internet with 3 Mb down and 512 kb up...these speeds are in megaBITS, not BYTES, like limewire displays. Divide by 8 to convert. This means that in Limewire, the fastest speed that I can expect is this: 3,000/8=375 kB/s down and 512/8=64 kB/s down.
You also have to take into account that people can limit how much others can download from them...Limewire allows you to determine how much bandwidth you want to allocate to uploads.
Hope this helps