OK, this is for the ppl getting slow speeds with torrents. I was also getting slow speeds untill MansoN pointed me in the right direction. For everyone using Azureus, if all icons in your health column are yellow, then you have a NAT problem. This means that your PC can initiate connections with peers, but they cannot initiate connections with you. So in effect you do not have as many connections as you could. Azureus has a built-in NAT test, but is not failsafe. Azureus reports that I have a NAT error, yet all my health icons are green and I have local and remote connections.
Like the earlier posts in this thread, you need to make sure that you have forwarded the correct ports in your firewall/router, and don't use the default port number. In Azureus you can make sure that you are recieving remote connections by right-clicking the download and select the peers tab. Have a look at all the connections, and if all of the are local, then you have a port-forwarding problem. If there is a mixture of local and remote connections, then everything should be fine and your health status should be green.
In Bitcomet you can check your incoming/outgoing connections by clicking on peers on the left-hand side panel. The is a column that will have either "L" (Local), or "R" (Remote). If you have a combination of L's & R's, then your port forwarding is OK, if there are only L's, then you need to sort it out, otherwise you will never get good speeds.
For everyone connecting through routers, if you are not sure of how to set port-forwarding on your router, google for example "+port-forwarding +azureus +wrt54g", without the inverted commas, and substitute azureus and wrt54g for your choice of BT client and router.
Sorry, the post is a bit vague and short, but too busy for much more detail. If all else fails, GOOGLE-Man's new best friend.