You can find the screen resolution easily from javascript and accordeing to that you can design your website;
see this code to find resolution of screen;
<script runat="server" language="C#">
public void Page_Load(Object sender, EventArgs e){
if (Request.QueryString["action"] != null) {
// store the screen resolution in Session["ScreenResolution"]
// and redirect back to default.aspx
Session["ScreenResolution"] = Request.QueryString["res"].ToString();
Response.Redirect("default.aspx");
}
}
// JavaScript code below will determine the user screen resolution
// and redirect to itself with action=set QueryString parameter
</script>
<HTML><BODY>
<script language="javascript">
res = "&res="+screen.width+"x"+screen.height+"&d="+screen.colorDepth
top.location.href="detectscreen.aspx?action=set"+res
</script>
</BODY></HTML>
Also you can desing a website so that it will fit to all resolutions;
there are some steps you need to follow for the same;
see these links which will give you exact information about the same;
http://windyroad.org/2007/05/18/resolution-independent-web-design/
http://www.entheosweb.com/website_design/advanced_web_design.asp
http://www.informit.com/articles/article.aspx?p=455372&seqNum=4
http://www.devcity.net/Articles/64/1/screenresolution.aspx