help in Regex in .net

Hi,I am new to regular expressions, I am having a problem regarding matching a specific keyword in certain condition.
string regexstring="\\bhtml\\b|[.]net\\b";Regex rgx = new Regex(regexstring, RegexOptions.IgnoreCase);MatchCollection matcol = null; string st_data = "I am a .net developer, but also know about asp.net, vb.net ; I work on c#/asp.net platform. I also know dhtml, html4.0, html/xml etc etc.";//I want the regex to capture all occureneces for html where html is a word seperated \b-->word boundary or is surrounded by decimals like html4.0 above. st_data = System.Web.HttpUtility.HtmlDecode(Regex.Replace(st_data, @"<(.|\n)*?>", string.Empty ...