Sussed - create a 'software instrument' track and I think by default it loads up a piano. Over on the RHS there's a couple of Tabs,
[attachment=106241:Screen Shot 2012-04-27 at 10.23.56.png]
Click the 'edit' one,
[attachment=106242:Screen Shot 2012-04-27 at 10.24.00.png]
and select EZdrummer from the bottom part of the drop down list,
You should then be able to drag and drop MIDI loops from the 'groove' menu in EZ Drummer -
[attachment=106243:Screen Shot 2012-04-27 at 10.25.23.png].
Loop away!