From the day I bought a laptop with windows vista 64 (in dec 2008), I
have been struggling to get a vpn client which works on it. Cisco
vpn3000 client does not support Vista 64 platform. There were few
options to vpn-connect my laptop:
1) Install another 64 bit OS (Open Solaris / Ubuntu / etc...) and run some vpn client from there.
2) Install Windows XP on VirtualBox (or any virtualization software), and run cisco vpn client from there.
3) Install Cygwin on Vista 64. Compile and run vpnc from there.
All these options works, but was painful to do it just to be able to
connect to vpn. Recently I heard about Shrew Soft VPN Client
(http://www.shrew.net/download/vpn) and gave it a shot. Amazing... It
works great on Windows Vista and Windows 7 64-bit platforms and it is
free. It supports importing .vpn and .pcf files (.pcf support is added
recently in 2.1.5 rc). I am very happy that finally some vpn client
woks on Windows 64-bit 
.