I do wonder, since you already have the A590 if you could keep your OS on that and use the internal as a "second" drive, which you could remove and mount in a PC with WinUAE to transfer files.
As Cammy says, it wouldn't be hot swap, so you'd have to down the machine for the swap. If it's an IDE port (I haven't really looked at the specs for the ACA520), I suppose you could run an IDE cable long enough (but not too long) to reach just outside the case to make the swap easier...
I've seen people mount their CD cards for their A600's that way, so they can more easily update them with WinUAE.
No idea if that would work, but it's a possibility..
desiv
