robfir: you should desactivate UP support in ->options ->speed -> desactivate UP support, since your computer makes an obvious poor UP. I would also get a LW 4.3.x version that has a better firewall and router detection http://www.limewire.com/english/content/beta.shtml This could help you become unfirewalled and thus complete more uploads.
-you should not be asked in the upload window for files you don't have, it is weird.
-it is normal that you don't upload total files if they are popular --- people are dling from multiple hosts to finish the transfer faster (hence only a part of the file they get from you)
-since 4.2.x versions LW can do firewall to firewall transfers, to verify if you can do those while being firewalled go in options->error reports->see an exemple, if this line say FWT Capable: true, you should be fine.

Ciao

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