Thanks so much for your replies.

The buzzing sound is not the fan, although that would make sense.
I actually paid for this version of limewire pro- can I delete and download again without paying for it twice?

It is a bit disapointing that that success rate on downloading is normal - That said, being new to this I am amazed at how much music etc is out there to download, and the quality of the songs that I have downloaded has been good. Are there any downsides to downloading programs? It seems to good to be true - For example - just did a search on a mac program ......- is it really possible this can be downloaded for free?! And the files are all different sizes, how do I know what that means? Is there any way of getting more info about something before downloading it - I guess this is what chat is for, (when/if it works)? Or is it better limewire etiquette to not ask annoying questions and just take your chances...

Anyway, thanks for explaining the files as well - starting to make sense of this!