As both machines are in a workgroup you may use passthrough authentication, create a local user on each box with exactly the same password.

If you want the sql server instance to copy the files out to the remote server you will need to run the sql server service under this local user account, otherwise use a scheduled windows task to copy the files for you.

For more on pass through and moving files remotely in a workgroup or cross domains see my guide at this[/url] link. The guide mentions Log Shipping but the principals are the same.