Thanks for the replies, yes my aim is to have the CIFS users read / write to the share. Bill, thanks for the info and link, however it appears that it doesn't quite match my requirement, it suggests a many to one mapping both ways rather than one to many. The only workaround I have been able to think of, that will suit my environment, is creating a windows domain account to match the relevant Unix accounts and set up the mapping as that user...
Domain\UnixUser1 => Unix1
Domain\UnixUser2 => Unix2
Domain\UnixUser3 => Unix3
This will work, however is not ideal for the users as they will be required to know the username and password for the mock Domain\UnixUser account and map as another user rather than straight in through their own domain accounts. I can obviously set the unix "other" permissions to allow them to read / write to the shares, but without the appropriate mapping this will result in nobody:nobody file ownership in unix which is not ideal.
Thanks for your help guys.