Transmission

Hi, I'm new to this torrent lark. One probably very dumb question:

1/ I began downloading a film of 686 Mb size, left Transmission running all night and by the morning it had said I'd uploaded 4GB or so! Aaagh! Does this mean I've burned half of my ISP's monthly limit of 8MB on downloading one film!? {I've now set my ratio to 1.00 to avoid this in future} And what exactly did my machine upload all night? I have no films (bar the one I just downloaded) on this machine so what else would be going - my music library?

Well, I guess it really does sound like you "burnt" half of your limit =/
As per what was shared: each torrent file only shares (uploads) small bits and pieces of the file you're downloading (or seeding) - it does not touch other files, such as your music library. It exchanges these small parts with the peers you're connected to (and the same is valid for them) in order to speed up the transfer for everyone - or at least it does so in theory =)

Many thanks Guilherme, that answers my question. But I feel that Transmission should really default to a 1.00 ratio so that idiots like me dont get caught out the first time they use the programme....

The default is the common-sense default - don't limit anything.

yeah most people go trough the preferences while first launching a programm (at least I do)