View a document (as byte[]) in some viewer

Here's the situation: You have a byte[] of a PDF and you want to show the user. How? Easy, just move it to a file and start a process against it. (note: this is a WinForms solution) Here, I'll show you what I mean:

static public void ShowDocument(byte[] letter, string extention)
{
    if (letter == null)
        throw new ArgumentNullException("letter");
    if (string.IsNullOrEmpty(extention))
        throw new ArgumentNullException("extention");

    string _FileName;
    _FileName = string.Format("{0}.{1}", Guid.NewGuid().ToString(), extention);

    string _FolderName;
    _FolderName = Environment.GetFolderPath(Environment.SpecialFolder.InternetCache);

    string _FullPath;
    _FullPath = System.IO.Path.Combine(_FolderName, _FileName);

    if (string.IsNullOrEmpty(_FullPath))
        throw new NullReferenceException("string.IsNullOrEmpty(_FullPath)");

    using (System.IO.FileStream _FileStream
        = new System.IO.FileStream(_FullPath, System.IO.FileMode.OpenOrCreate))
    {
        _FileStream.Write(letter, 0, letter.Length);
        _FileStream.Close();
    }

    System.Diagnostics.Process.Start(_FullPath);
}