Support for the Windows Server 2003 Network Access Quarantine Control feature in ISA Server 2004: http://support.microsoft.com/default.aspx?scid=kb;en-us;888651
Site-to-site VPNs in ISA Server 2004: http://support.microsoft.com/default.aspx?scid=kb;en-us;888711
How to configure a VPN server using ISA Server 2004: http://support.microsoft.com/?scid=kb;en-us;837355&spid=2108&sid=global