2 factor authentication

Hi all,

I'm looking for information on how to implement 2 factor
authentication (smart card, etc) on stand-alone WinXP Pro
laptops. I know that in an AD environment smart card
authentication is an intrinsic feature - how do you
protect non-AD connected computers, such as travelling
laptops that do not connect back to the corp office, with
this technology?

I tried a 3rd party solution (PassHolder) but it didn't
work very well and I ended up killing the admin access to
the token. Anybody have any suggestions? Thanks.