How to extract URLs (href property) from HTML

protected ArrayList GetUrl(string text)
{
    ArrayList listURL = new ArrayList();
    Regex r = 
        new Regex("href\\s*=\\s*(?:(?:\\\
        "(?<url>[^\\\"]*)\\\")|
        (?<url>[^\\s]* ))");
    MatchCollection mathColl = r.Matches(text);

    foreach (Match math in mathColl)
    {
        foreach (Group gr in math.Groups)
        {
            listURL.Add(gr.Value);
        }
    }
    return listURL;
}