Ordering not acting right.

I have a text field which I use to store names ( lastname, firstname )
and suppose we have the following 3 authors in the field:
   ta, a
   ta, z
   tab, a

I would expect them to show up in the order shown above when I select
this field and order it by it, but instead I get:

   ta, a
   tab, a
   ta, z

Some one has suggested that this may have to do with my locale setting.
I'm not an administrator so I'm not sure what how to check for the
locale setting or what to change it to.  Does any one have any
suggestions?

I'm using postgres 8.1.11.

Thank you!
Jose