Single Signon and Integration with Active Directory

Hi,

We have a requirement to integrate Active Directory with SAP and implement Single Signon solution. Our Active Directory is running on Windows 2003 and we are having systems 4.7 , ECC6.0 which run on Linux OS in our landscape.

Can anyone of you help me by answering following questions

1. Is there any need of any third party solution(tool) to integrate Active Directory and SAP and activate single signon?

2.Is there any difference in integration from SAP 4.7 and ECC6.0 of SAP on Linux OS with Active Directory ?

3. If possible please share any documents or links on above issue.

Suitable answers will be rewarded with points. Thanks in advance for your help

Regards

Murali