400d's usb

Is this a specialised cable or will any of the myriad of usb cords I have collected do the same job?

I, for one, need a little more info.

Far as I can tell, if you have a cord that will fit any USB socket, it ought to work. But some USB cords are "directional," while others aren't. If you can plug it in, more than likely it'll do the job.

As for 400d, I have no idea what you're talking about.

The Canon EOS 400d

As long as the cable will fit the socket, it doesn't matter which one you use.