How to copy string content to unmanaged memory block in Delphi for .Net?

var
MyString: String;
UnManagedPtr: IntPtr;

begin
....
Marshal.Copy(MyString.ToCharArray, 0, UnManagedPtr, MyString.Length);
...
end;

Various copy methods are available for reference in M$DN
http://msdn2.microsoft.com/en-us/library/ms146626(VS.80).aspx