As I understand the term "Smart Card", it is an authentication tool. It is one way to identify a user, it uses a Smart Code token exactly the way that Windows itself uses a password.
The real advantage to using a smart card is that A) it is difficult to copy and B) it is easy to pass to another user. While people might leave their password taped to their PC or their smart card lying on their desk for someone to "borrow", it isn't easy for a user to copy their card and give a copy to another person (either deliberately or accidentally).
You might also want to consider
RSA tokens. These would be much less expensive for your use (due to state contracts) and they are also both more secure and more flexible to use than smart cards.
-PatP