I've been chatting around a bit and discovered that the fact that "vpnc doesn't work" is a myth - at least in my case.
Using vpnc doesn't only work, it's also a lot more convenient, because you don't have to keep upgrading manually.
If you're using Ubuntu, all you have to do is install the package vpnc. After that, Ubuntu will take care of the upgrades.
All you need is a conf file for vpnc which tells you how to connect. Luckily, vpnc provides a translate script which converts a PCF file into a vpnc conf file, it's called pcf2vpnc. In my case, it's in /usr/share/vpnc, so I ran
$ /usr/share/vpnc/pcf2vpnc vpn-v1.pcf
and the output is the ready conf file. Save that as /etc/vpnc/YourVPN.conf (you need to do that with root-privileges, i.e. use sudo) and you can start the whole thing with
$ sudo vpnc YourVPN
To terminate vpn connection, run
$ sudo vpnc-disconnect
to restore routing.
PCF files usually use crypted group passwords. You can decrypt them at this website: http://www.unix-ag.uni-kl.de/~massar/bin/cisco-decode
http://www.penlug.org/twiki/bin/view/Main/CiscoVpn is a pretty outdated site on vpnc, but can give some insight.
This is already a lot better than the cisco client, but there's more good news: vpnc integrates into network-manager, and there's a KDE gui called kvpnc. As soon as I'm up to date on those, I'll finish the trilogy and hopefully we're back to the world where ordinary people can use VPN from their laptops.
