I was not able to install Cisco VPN on my new Windows7. After a lot of search, I got this fix from this blog. Edited a bit the way I installed.
 

Download the Citrix DNE Update and install it.  - 1)  winfix.exe 2) dneupdate.msi

Reboot

Make sure you have Cisco VPN Client 5.0.4.0300 (or newer, if available) [...]