Try AirTrafficControl downloadable free here:
AirTrafficControl 2.0.1b400 - Mac OS X - VersionTracker
to check your connection speed over wireless. It is a widget that shows all available wireless networks and the ACTUAL speed of your current connection. While you can achieve a wirelessG speed of 58mb/s if there is interference airport will back off on the connections speed automatically. Then reset your quicktime preferences for the actual connection speed.
AirTrafficControl 2.0.1b400 - Mac OS X - VersionTracker
to check your connection speed over wireless. It is a widget that shows all available wireless networks and the ACTUAL speed of your current connection. While you can achieve a wirelessG speed of 58mb/s if there is interference airport will back off on the connections speed automatically. Then reset your quicktime preferences for the actual connection speed.