External HD though Airport Express?

I don't think anybody has tried that, since it would be relatively pointless.

 

Now there's a way to encourage people to help you in the future. Perhaps no-one spotted it who knew the answer...

And no, you can't. The USB port will charge an iPod or work with a printer but not with a HD.

 

Either that, or build (or buy) a cheap used computer, throw a copy of Windows server on it, connect the hard drive to it and share the drive over the network. That's the solution I chose.

 

No need for windows... or an expensive mini.

If you've got an old PC laying around put freeNAS or a linux distro on it. FreeNAS basically makes the PC into a network attached storage device and is super easy to set up. Linux is a little bit harder, but once you get samba configured it's not too bad. That's what i've got at home and it works great.

If you're really set on a mac, buy an old G3 or G4 tower and use that. There's more internal space then in a mini, you can put a PCI raid card in, and the whole thing will be pretty cheap.

 

Remember that the maximum speed of 802.11g (Airport) is about one 1/7th of the maximum speed of wired USB (someone correct me if I'm wrong). If you're using your Airport network for other stuff too (music streaming, Internet access), that will bring the speed down further.

I don't know how much of a headache this would be to you, but its something to consider before you rush out and invest in Network Attached Storage.

HTH
SL