"In this thread Boot Camp: Networking, a reader says:
One thing that may be affecting the behavior of AirPort throughput under WinXP vs. OSX is AppleTalk. AppleTalk is horribly inefficient, so if it's enabled under OSX, you will most likely see worse performance w/ AirPort than under WinXP, since WinXP doesn't support AppleTalk.
Although I'm not a Mac user, it may be that disabling AppleTalk might improve AirPort throughput."
Well, upgrading the firmware seemed to do the trick. It was an obvious thing to try but I didn't get round to it until just recently. The exact cause is still unknown.
