I've read through dozens of threads and howtos and websites but can't seem to find a solution for how to connect my Kubuntu box to a corporate VPN.

From Windows, I'd do the following:

* Use Network Connection Wizard to create a VPN
* Give it a name
* Enter the VPN server IP
* Open it for all users
* Double-click the VPN connection and enter username and password, click Properties
* Options tab - tick all boxes
* Network Management tab - Select Automatic, then TCP/IP, Properties, Advanced
* General tab - untick the box so as to allow normal internet connection as well
* DNS tab - add 10.0.0.2 and the DNS suffix COMPANY.LOCAL
* WINS tab - add 10.0.0.2 and activate NetBIOS with TCP/IP

Using network-manager or the pptpconfig tool I can't find all the same options and the connection fails with a MSCHAP authentication error.

Can anyone help?

Here is a description for gentoo and vpnc
http://www.gentoo.org/doc/en/vpnc-howto.xml

Maybe can use that as a role model for your Kubuntu distribution -- except for compilation and installation of the needed software packages it is pretty generic...

I think he is actually using a PPTP vpn for that you will need the pptp client

Then you can configure a peers file and dialout. instructions are here to do that http://pptpclient.sourceforge.net/

If you need a gui you can use pptpconfig from the same site our if you are using network-manager you can use that but it only works if your outbound interface is being managed by network manager.