I have only just installed LW basic and I am new at peer to peer. I have NetTraffic running in the background which shows realtime traffic on my router connection. I am worried by intermittent traffic both upload and download when I am not downloading anything with LW. Also, when I close LW by clicking the X this traffic still pursists.
WHAT ARE THESE BACKGROUND UPLOAD AND DOWNLOADS DOING TO MY PC?

Nothing much, just keeping you online which is completely normal activity. If
you really want to close LimeWire completely, instead of just shrinking it down
to an icon next to the clock, you will have to use Exit in the File menu or
right-click thast icon and select Exit.

In short, those are not uploads and downloads but just innocent housekeeping traffic.

I have noticed some other processes whilst using LW today;
The worrying traffic I spoke of only starts when I have initiated a download, and continues after download has finished.
There is no Exit command in the drop down file menu, only Close. When using the Close command, the traffic continues.
The traffic only stops when I right click on the Icon and select Exit.
Is this innocent houskeeping you speak of adding to my download limit to any serious degree?

Not really. It's barely a whisper, just enough to stay connected.

If the file is really popular, you might get occasional download requests
for parts of it but you can control that by going to the library view, finding it
(in Saved Files), right-clicking on that file and making sure it's not shared.
You can do that to the Saved Files folder too. The odds of anybody actually
downloading the new file are tiny but this will make the odds go down to zero.