allowing users to mount smbfs

[MRZ <mrz.pct@home.com>]

Hello again everyone.

I'm trying to configure my potato box such that any user can mount/unmount the share(s) on an NT box I have. Naturally when I say any, I 
mean any user who also exists on that NT box. Keep in mind that I'm not trying to make shares available to others from my 
potato box; for that I have samba installed.
It's been explained to me that to do this I need simply go root, and add a reference for this share to fstab. 
Once this is done then any user can "mount /<mountpoint>", enter their p/w and it will be mounted for that user session. 

Well I've made the entry as best as I understand, but am having a peculiar problem for which I ask everyone's help to solve.

I would like to have this behave the same way for all users so I've chosen to make the mount point "/mnt/ntbox".  
Here is what I tried adding to fstab:
"//ntbox/share 	/mnt/ntbox	 smbfs	defaults,rw,user,noauto 0 0" (without the quotes, natch!)

So I then open a terminal and try "mount /mnt/ntbox"; I'm prompted for my password which I enter.
But the process fails with:
"cannot mount /mnt/ntbox: Operation not permitted
smbmnt failed: 1"

But: If I change the reference <mountpoint> to "/home/user/somedir" and repeat the attempt 
at a terminal, "mount /home/user/somedir" it works fine.

What am I doing wrong?

Thanks!
Marc.