Sounds like you need to adjust your upload bandwidth. In Limewire you can adjust it by going to Tools>Options>Uploads>Basic, adjust the slider and click apply.
Try doing a couple speed tests to see what your upload bandwidth is. Then set it to about 80% or so (you may have to experiment a little). So you save some for other things.
http://www.dslreports.com/stest http://www.speakeasy.net/speedtest/
As foolofthehill suggests, don't kill the uploads just adjust your bandwidth. Sharing is what it's all about
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