A500s are great. Get yourself a Derringer 030, a Dataflyer IDE, and away you go! No screwing around with clockports! If you want, you can even add a Zorro II bus and have a network and video card too.
You *can* use an ATX power supply, you will have to wire it yourself. You *can* use PC floppies, but you will gain nothing over the built in A500 drive.
