it sounds like it could be 1 of 2 things. the first is the encoding rate, which you can re-encode the video file to take care. the second may be that your devices are too far from the router to maintain an 11mbit connection. if this is the case, they can drag the connection down to whatever the lowest speed is. if your laptop is only getting a 2mbit connection, your axim will only get a 2mbit connection and that bandwidth is shared between two devices.
i would try the encoding first, though, as that's the easiest thing to fix. use
virtualdub to re-encode the file with a lower bitrate and you may find that it resolves the issue.