Two suggestions. In the G604T were you using MAC addresses as the security as well? Not sure if this is the answer because you can ping without encryption switched on. Try entering the MAC address of the Vaio.
Do you have a firewall on the Vaio as well as the G604T? If so make sure that the range of valus 192.168.1.1. to 192.168.1.250 is in the "trusted zone" and temporarily turn off the router firewall. Remember to save the router settings in Tools>System Settings and then restart both the router and laptop.