[U2Lynne]

All it means to be firewalled is that you may not connect to other people who are also firewalled. So, if you are on a torrent with a lot of non-firewalled people, everything will run just fine. However, if you get on a torrent that mostly has firewalled people, then you will only be able to connect to the non-firewalled people and speeds may be much lower (because don't forget that those other firewalled people may only connect to the non-firewalled people also).

(Sometimes I go firewalled for no known reason, but it usually disappears either in a couple of hours or after stopping/starting the torrent.)