Cannot connect to NFS share on Solaris box from Win2K3 R2 server

I'm trying to set up my Windows Server 2003 R2 server to connect to a Solaris
server via NFS. I have installed the relevant bit in Windows, and have got as
far as it giving me error 1326 ("Logon failure: unknown username or bad
password"). I'm pretty much stuck. I have entered various UNIX and Windows
usernames/passwords and nothing works. Can anyone tell me how to fix this?

One thing I did find odd is that the Windows documentation is not clear
about whether user name mapping is actually required to get the NFS client
talking to a UNIX box. I would have thought that using the UNIX username and
password as part of the "mount" command would work without any special
mappings.

Here is the command I'm using on the Windows machine to mount the NFS share:

mount -u:andrew SXCE65VM:/export/public/test Z:

I then type the correct password, then get error 1326.

Any ideas?

Andrew.