Chop words

/// <summary>
        /// Returns part of a string up to the specified number of characters, while maintaining full words
        /// <para>http://www.mikesdotnetting.com/Article/137/Displaying-The-First-n-Characters-Of-Text</para>
        /// </summary>
        /// <param name="s"></param>
        /// <param name="length">Maximum characters to be returned</param>
        /// <returns>String</returns>
        public static string Chop(this string s, int length)
        {
            if (String.IsNullOrEmpty(s))
            {
                throw new ArgumentNullException(s);
            }
            var words = s.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
            var sb = new StringBuilder();
 
            foreach (var word in words.Where(word => (sb.ToString().Length + word.Length) <= length))
            {
                sb.Append(word + " ");
            }
            return sb.ToString().TrimEnd(' ') + "...";
        }