aspx to html convertion ( crawling ) problem

Question

Hi All,
I'm developing a new seo tool.I began my tool by converting aspx pages to html pages.I'm doing this by

mywebReq = WebRequest.Create(pageURL);
mywebResp = mywebReq.GetResponse();
sr = new StreamReader(mywebResp.GetResponseStream(), System.Text.Encoding.UTF8);
strHTML = sr.ReadToEnd();
sw = File.CreateText(filePath+"temp.html");
sw.WriteLine(strHTML);

codes.But didn't get the exact page html from my converted html page.

this is converted html page : http://www.videoticaret.com/city/temp.html

this is aspx page :
http://www.videoticaret.com/City/Default.aspx?s=1&c=6

In html page the menu doesn't work, but in aspx page menu works.

When i compared the two page by winmerge tool ( which compares word by word) , i saw some style texts and some CDATA text not takes place in html page.

I'm asking that question , WHY ?

And, How can i solve the problem ?

Thanks,