Hi all, after some help. Having got my board I've just tried to get it running. I had a 16GB SD Class 4 card available. It had a few old media files on it and was working OK. Using the wheezy image I used dd (I use Ubuntu as my working OS) to copy the .img over. This seemed to work OK and I remembered to sync before removing the card.
When I put it in the board and powered on nothing happened, however. Power LED lit and the HDMI port was outputting a signal according to the HDMI switcher gizmo I use so the hw side seems fine. When I put the card back into the desktop it didn't mount. I could see it in the Disk Utility tool and I could delete the partition although having done that it wouldn't create a file system on the card as it thought it was ro. I've had flakiness before with Linux not recognising removable media before so I booted Windows 7. This found the card and told me it needed formatting to be useable so I let it do that and copied a file to it to confirm that it's working. So in due course I'll boot Linux again and this time I'll try using the GUI image writer instead but if anyone has any ideas as to what could have gone wrong first time around please fire away.