Is it better to use the [using] directive in C# or the [dispose] method? Does this apply to external (COM) objects?

Programmer Question

I've seen this be a lively debate between the Microsoft C# folks and Microsoft Exchange CDO support groups.

What is better, the using directive, or the dispose directive when finished with an object?

 using(FileStream fileStream = new FileStream(
            "logs/myapp.log",
            FileMode.Open,
            FileAccess.Read,
            FileShare.ReadWrite))
        {
            using(StreamReader streamReader = new StreamReader(fileStream))
            {
                this.textBoxLogs.Text = streamReader.ReadToEnd();
            }
        }

On the other hand, when I'm dealing with System.Net.Mail, I'm told I need to Dispose() of the object to release any stray locks.

Is there any consistent guidance? How do I tell what is more appropriate in a given situation for a given object?

Find the answer here