Thanks to Jo, super-sysadmin, who pointed me at two links that finally got me connected to our work VPN after I switched from Debian to Ubuntu. The trick is not to use the old pptp-config, but instead switch to a new package – network-manager. Brian Daley wrote up the the actual VPN Connection instructions, and I also had to follow the advice to disable network interfaces in /etc/networking/interfaces so that the new package could manage them. After fiddling with the VPN configuration settings (disable EAP-Authentication, and disable authenticate peer), I was able to connect. As you can imagine, I was quite overwhelmed by the excitement.