Need some feedback. What do you think about storing my data like

Hi,
I need to store a hierarchy in my database (a tree)
I have 3 types of data: Cases, Groups and Users. I can have any
combination of them.
Check the following link ('Groups', 'Cases', 'Users' and 'Tree' will be
tables in my database):
http://www.lemforever.com/temp/tree.jpg
What do you guys think? Do you think is a good solution? I still want to
have a relational database
and I don't want to violate any integrity rules.
Thanks a lot.I just realized that I could have used my previous post for asking that.
Sorry about that.
If you have any feedback please use either one.
Thanks

Need Help.

I m using SQL SERVER EXPRESS edition for storing user login information. I have use built in login controls in my application. Login is working properly, user are also created but i also want to assign roles to users and modify their details programmatically.

How can i do this ? Plzzzzzzz Help. Its urgent.

These resouces should help point you in the 'right' direction:

Security -Giving Permissions through Stored Procedures
http://www.sommarskog.se/grantperm.html

SQL Server 2005 Security
http://msdn.microsoft.com/msdnmag/issues/05/06/SQLServerSecurity/