I spent the other night with my friend Elfine, trying to figure out how to get her EeePC on the school's wireless. I did it! If you run
sudo route del default, just before starting VPNC, it'll work. It turns out the EeePC doesn't replace the default route—instead, it adds a second default route, which simply doesn't work. Delete the default route before starting the VPN, and it won't get all mixed up. Your internet will work.