External USB ext2 drive and samba/Windows

[scott-DPNOqEs/LNQ at public.gmane.org (Scott R. Ehrlich)]

I have an external USB2 hard drive connected to a RHEL5 server in a 
samba/NIS environment.

People are able to read and write to the server's RAID drives fine from 
Linux and Windows XP systems.  But, only the Linux machines can read/write 
the USB hard drive - the Windows systems, whether the mounting is via 
drive letter or UNC, can only read it.

The Windows machines are part of a samba-based domain.

I have verified group ownerships and user/group/other permission bits of 
the mounted USB hard drive.  I _should_ be able to write it, but Windows 
keeps giving me permission denied.  A reboot of the Windows systems 
doesn't help, either. Other domain Windows machines behave the same.

What am I missing?

Thanks.

Scott