Cisco finally released a version of the Cisco VPN Client that works on 64bit machines and is IPSec capable.
From their site:
"The new release VPN Client 5.0.07 supports the Windows Vista on both x86 (32-bit) and x64. Refer to the 5.0.07.0240 Release Notes for more information."
I just installed it on my Windows 7 x64 laptop and it works just fine.