I have a Dell XPS 15 with dual boot windows 7 ultimate and Ubuntu 11.10 and the wireless connection is really bad on Ubuntu, I have 2-5mbps in Ubuntu and keep losing the connection for 5sec, but in windows I have 20mbps and its good and fast...
I have Intel Centrino wireless-N 1030
I have tried to turn Power Management to off and it got up to 7-10mbps so that helped now but i still keep losing the internet connection.