There should be a MS-CSP-wrapper for the SAL or PKCS#11, which allows to use the supported smart cards on Microsoft-platforms
Updated by Tobias Wich about 2 years ago
The above link seems to be dead and there seems to be no replacement. Every vendor just implements CSP atop their implementation.
There is a PKCS11 .NET implementation, but that does not expose CSP stuff, so it's not really useful here.