.NET Active Directory Wrapper    
Access Active Directory From Your C# or VB .Net Code
 

Active Directory
Introduction
Objects
Object Properties

DirectoryServices Namespace
Introduction
DirectoryEntry Class

How to .. in C# .NET
Create User
Disable User
Enable User
Authenticate a User
Change User Password
Get DirectoryEntry of a user
Get Users in a Group
Get Object Property

Other Resources
References

Retrieving a property of an object

public static string GetProperty(DirectoryEntry oDE, string PropertyName)
{
if(oDE.Properties.Contains(PropertyName))
{
return oDE.Properties[PropertyName][0].ToString() ;
}
else
{
return string.Empty;
}
}