I navigated the Cisco Website (http://www.cisco.com/cgi-bin/tablebuild.pl/windows) to find a 64 bit version of the Cisco VPN client and was unable to identify if there was one.
What software can be used to connect on a Windows Vista client to obtain Remote Access?
There isn't one - quote from the VPN client FAQ
Q. Does Cisco provide a VPN Client for Windows Vista?
A. At the time of writing (June 2007) Version 5 of the VPN Client is available for 32-bit Windows Vista. Support for 64-bit Windows Vista is not available at this time.
I believe this is still the case.