linux – Non-Official Cisco VPN Client for Linux

Hmm, nobody mentioned Shrew Soft VPN Client yet ? It's a free (as in beer) and cross platform VPN client that compatible with Windows 64 bit. Although free, but support from the author has been great. Currently it doesn't support hybrid xauth+certificate mode but the feature will come soon.

Lancom also provides a 64 bit VPN Client for Windows, but IMO they just resell/rebrand NCP's Client.

You can also try TheGreenBow VPN Client, which is a bit cheaper (56 EUR) than NCP/Lancom's client.

Shrew Soft VPN client is a free IPSec client that runs on 32-bit and 64-bit Vista.

It does not support existing Cisco VPN profiles (.pcf files) though.

EDIT: Cisco VPN profile import was added in version 2.1.5