Parsing HTML String

You can use the excellent HTML Agility Pack.

This is an agile HTML parser that builds a read/write DOM and supports plain XPATH or XSLT (you actually don't HAVE to understand XPATH nor XSLT to use it, don't worry...). It is a .NET code library that allows you to parse "out of the web" HTML files. The parser is very tolerant with "real world" malformed HTML. The object model is very similar to what proposes System.Xml, but for HTML documents (or streams).

Take a look at using the Html Agility Pack

Example of its use:

 HtmlDocument doc = new HtmlDocument();
 doc.Load("file.htm");
 foreach(HtmlNode link in doc.DocumentNode.SelectNodes("//a[@href]")
 {
    HtmlAttribute att = link["href"];
    att.Value = FixLink(att);
 }

You can use the HTML Agility Pack and a little XPath (it can even download the document for you):

HtmlWeb web = new HtmlWeb();
HtmlDocument doc = web.Load("http://www.abcd1234.com/abcd1234");
HtmlNodeCollection tags = doc.DocumentNode.SelectNodes("//abc//tag");