Here's something that AirPort Extreme users may already know: according to Apple, the use of OS X Leopard's Time Machine backup with hard drives connected via USB to the AirPort Extreme is currently "unsupported." That's Apple's official statement, but that's not really the case right now.

Let it be known that the current firmware update actually permits the use of AirPort Extreme-connected hard drives for backing up through the Time Machine. All you need to do is to upgrade your firmware...yes, right now, since Apple may really take out the compatibility between the AirPort Extreme in a future update.

Of course, before you do so, check and see if the firmware update will remove the feature that enables connectivity between the AirPort Extreme drive and the Time Machine.

Some Apple users have reported that AirPort Extreme being an "unsupported feature" also meant that Apple's customer service will not provide any assistance if you call in asking for help to back up drives connected to the AirPort. Of course, if you don't want to go through all the hassle, you might as well go all out and purchase a Time Capsule.