Originally posted by Sandwich
Ok, clarification needed...from what little I read of BT, it requires one to upload at the same speed as you download. In other words, on my 1.5mbit/96kbit (down/up) ADSL, I'd be limited to a 96kbit download under ideal circumstances?
The way it works is: You connect to the Tracker. The Tracker keeps note of everyone who's currently downloading the file (or has finished downloading and left their torrent-window open). You then download chunks of a file from other people in random-order, depending on what chunks they've already downloaded.
So if someone has a chunk you need, the Tracker says "Hey, you, give that guy chunk 1754". It does this so you can download some of the file from people who haven't got the complete file themselves yet.
And your uploading fluctuates depending on how many/which chunks you've got and which/how many other people have.
So if there are 40 people just starting to download the file and you've already got 90% of the file from whomever started it, you'll be doing

of uploading. But if you've got 10% and there are 40 people who've already got 90% then you'll be downloading really fast.
This is why people are always screaming "Leave your torrents open!!!!".
The more complete files on a torrent, the less it has to suck BW from people still downloading and the more chance of finding a chunk you need on a non-clogged source.
But generally, on a torrent with a decent number of people on it, you'll get about a 10:3 ratio.