mini mac hard drive upgrade - how to transfer data

Hi, I have just upgraded the hard drive in my mini mac and the process has all gone smoothly. Phew!!

I've put the old drive in an external case and I'd like to transfer some of the files across. I'm connecting the old drive via a USB cable however its not showing up on my updated mac.

Is there a jumper setting or some config I can do on my mac to allow it to identify the old drive via the USB cable??? Any thoughts would be greatly appreciated!

Firstly is 'External Disks' selected in the Finder preferences?

If so start the Mac Mini, then connect up the external HD and see if it shows up that way. USB even USB 2 is an awful slow way of doing things compared to Firewire.