Thanks very much for helping me but I've got weird results.
The other day I brought a Sony MDS-JE780 thinking that if I couldnt get my MZ-N910 to work I'd use this to put music on my minidiscs, anyway after much farting about and downloading this would only 'speak' to my XP laptop and sonic stage worked fine. Well after sftp's advice this morning I downloaded the 64-bit driver for NetMD in his link which worked great for the MDS-JE780 which I can now use with my windows 7 pc where all my music is .
Only thing now is that didnt work with my lovely N910. I dont think it's a driver problem, I think there is something wrong with the player itself like the the usb socket has become unresponsive which is really annoying because there's no reason for it as I really look after my gadgets.