Read the sticky about configuring Limewire at the top of the Open Discussion forum (here). It isn't only directed towards broad-band users since it tells you how to configure it depending on your connection speed.
If you read it, you'll notice that I also suggest people to configure uploads: by configuring them that way, I manage to get more completed uploads as I'll have less available upload slots, but the people that download from me get their files a whole lot faster. Being able to download a file faster can mean:
-you have less chances of the download being canceled/dropped/whatever because of hosts (or you) going offline.
-you complete the download faster, thus releasing an open slot for another user, who'll also have a faster download. In other words, instead of having 100 users (again, a little exaggeration...) uploading from you with speeds ranging from a few Bytes to a couple of KiloBytes which means they would get their files after an hour, you get 10 users who will dld from you at full speed: they'll get their files in a couple of minutes, thus letting in the next 10 users come in and start downloading.

Also, I think banning a host is more of a function reserved for users serving bad files, viruses and various other stuff like that.
Besides, some people have IP adresses that change every now and then.

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iMac G4 OSX 10.3.9
RAM 256MB
LW 4.10.5 Basic
ADSL anything from 3 to 8Mbps/around 1024kbps

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