> While Microsoft Windows XP isn't free, it does include a VPN client by
 > default. You can create a VPN device by adding a "dialup" location and
 > choosing the PPTP (VPN) option. Then you configure m0n0 for PPTP.
 >

Some people don't like to use PPTP in Windows for security reasons, see:
http://www.schneier.com/paper-pptp.pdf

Windows XP also has (limited) IPSec and some OSS projects try to build a 
  GUI for it, e.g. http://sourceforge.net/projects/ivpn/

I like the idea of using a full featured IPSec client and will give it a 
try.

Thanks for the hint, Don.

Regards

-Bjoern