[Samba] Solaris 10 and "store dos attributes"

[James]

I'm having trouble with files being marked read-only in Windows because the
Solaris file owner does not have write-permissions on the file; group-write is
allowed:

-r--rw----   1 user  group      32 Feb 13 14:19 testfile.txt

I thought that setting "store dos attributes = yes" for this share would allow
the "read only" setting to be stored in extended attributes, but it doesn't seem
to be working - does Solaris 10 support extended attributes as needed by Samba?

I'm using Samba 3.0.24 on Solaris 10, configuration file or the share below:

[TEST]
   comment = server vartmp
   path = /var/tmp
   browseable = yes
   public = yes
   guest ok = yes
   writable = yes
   force create mode = 0664
   force directory mode = 0775
   map hidden = no
   map system = no
   map archive = no
   ea support = yes
   store dos attributes = yes

Thanks in advance -- James