How can I display my groups in a nested list order on the left-hand side of
the pane; so I can click on each individual group and see what's in them?
Have you ever noticed when you exported your contacts that Entourage
mentioned, it didn't export groups? If you don't enter the contacts in the
Address Book as well as in the group, you could loose all that data if there
were problems.
I suggest you add (drag the address) of each group member to the Address
Book and assign a category. I also use a method of using a category/tag. If
you had a lot of groups, you might not remember the name when you start to
address a message, but since they will all start with group, then it's easy
to find it in the list.
Group: Christmas Cards
Group: Soccer team
Group: Party
Once you add all the contacts to the Address Book, you can sort by category
to show just that group. When you sort by category, you will be able to see
which contacts are in multiple groups
I also suggest that you add the category "group" to each group. You can use
the categories in custom Address Book Views in addition to the simple find
popup "Category is".
Hope this helps!