Vista - Sharing contacts between multiple computers

I've seen similar questions on this forum, but would like to ask the question
in a specific way:

Within a home network, is there a way to share contacts between multiple
computers and users? Specifically, I would like contacts shared between me
and my wife, and the contacts stored on our network NAS (network attached
storage - network file server).

Environment: Windows Vista Premium (my computer), Windows Vista Basic
(wife's computer), Windows Live (most apps) installed on both computers, I
use WL Mail, she uses Juno (through web browser), both have latest WL
Messenger installed, we both have Windows Live IDs.

I don't want to constantly "export and import" - I want all changes to be
visible by both users (me and my wife).

I can share my Contacts folder through Vista (as a shared folder), but that
requires my computer to always be on. I would rather store Contacts on a NAS
folder - is it possible to "redirect" where Contacts are stored, through a
runtime environment variable, or a shortcut, or some other mechanism?

A response to a similar question on this forum suggested creating a Windows
Live ID that is shared for the family, and managing contacts that way. What
does this imply for the interaction between WL Mail and contacts (for me) or
WL Messenger and contacts (for my wife - Messenger is how she will access the
contacts)? Do I have to sign in twice when using WLM? I definitely like the
synergy between WLM and Contacts and do not want to lose it.

Where would the contact data be stored for the "shared Windows Live id"
approach? On Windows Live web servers? (This would be acceptable as long as I
have full control of the Contact data, and there's an easy way to do an
initial export and import into the new Live ID.)

Other approaches or suggestions?

Many thanks!

Cliff