Im told that 64bit Vista is not on the roadmap for the Cisco VPN Client. You have to move to the AnyConnect VPN Client and ASA headends if you have Vista 64bit.
Most likely The WiFi adapter still has a default MTU confiured. Run the SetMTU.exe to reduce the MTU size and reboot. Normaly and MTU size of 1300 will work. Some ISP's may require a lower setting.
