Regarding SSO between windows and portal

Hi

We are trying to establish SSO between windows and portal using kerberos authentication.

We have gone through the following link:

http://help.sap.com/saphelp_nw04/helpdata/en/43/4bd58c6c5e5f34e10000000a1553f6/content.htm

Still that is not clear.

Can anyone suggest what are the steps to achieve this task?

Also can anyone let us know what is KDC and SPNegoLoginModule? Is that anything that has to be downloaded?

Is there any step by step guide to achieve this task?

Regards

Yoga