I wanted to provide better code, please take a look at this:
<%@LANGUAGE="VBSCRIPT"%>
<%
started = request.QueryString("start")
ended = request.QueryString("end")
imps = request.QueryString("imps")
imp_per_day = "0"
duration = "0"
if started <> "" and ended <> "" then
duration = DateDiff("D", started, ended) + 1
month_total = DateDiff("M", started, ended)
end if
if duration <> "0" and imps <> "" then
imp_per_day = imps/duration
imp_per_day = round(imp_per_day,0)
end if
lastDayOfThisMonth = DateSerial(Year(started), Month(started)+1, 0)
lastDayOfThisMonth2 = DateSerial(Year(lastDayOfThisMonth+1), Month(lastDayOfThisMonth+1)+1, 0)
%>
<html>
<head>
<title>Untitled Document</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</head>
<body>
<form name="form1" method="get" action="date.asp">
<table border="1" cellpadding="0" cellspacing="0" bordercolor="#000000" style="border-collapse: collapse">
<tr>
<td><table width="100%" border="0" cellspacing="2" cellpadding="2">
<tr>
<td width="65%" bgcolor="#CCCCCC"><strong><font size="2" face="Verdana, Arial, Helvetica, sans-serif">Start
Date:</font></strong></td>
<td width="35%" align="right" bgcolor="f4f4f4"><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><%=started%></font></td>
</tr>
<tr>
<td bgcolor="#CCCCCC"><strong><font size="2" face="Verdana, Arial, Helvetica, sans-serif">End
Date:</font></strong></td>
<td align="right" bgcolor="f4f4f4"><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><%=ended%></font></td>
</tr>
<tr>
<td bgcolor="#CCCCCC"><strong><font size="2" face="Verdana, Arial, Helvetica, sans-serif">Duration:</font></strong></td>
<td align="right" bgcolor="f4f4f4"><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><%=duration%> days</font></td>
</tr>
<tr>
<td bgcolor="#CCCCCC"><strong><font size="2" face="Verdana, Arial, Helvetica, sans-serif">Impressions: </font></strong></td>
<td align="right" bgcolor="f4f4f4"><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><%=imps%></font></td>
</tr>
<tr>
<td bgcolor="#CCCCCC"><strong><font size="2" face="Verdana, Arial, Helvetica, sans-serif">Imps
per Day:</font></strong></td>
<td align="right" bgcolor="f4f4f4"><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><%=imp_per_day%> </font></td>
</tr>
</table></td>
</tr>
</table>
<br>
<table width="700" border="1" cellpadding="0" cellspacing="0" bordercolor="#000000" style="border-collapse: collapse">
<tr>
<td width="754">
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tr bgcolor="#999999">
<td width="8%"><strong><font size="2" face="Verdana, Arial, Helvetica, sans-serif">Entry:</font></strong></td>
<td width="19%"><strong><font size="2" face="Verdana, Arial, Helvetica, sans-serif">Month:</font></strong></td>
<td width="24%"><strong><font size="2" face="Verdana, Arial, Helvetica, sans-serif">Start
Date:</font></strong></td>
<td width="25%"><strong><font size="2" face="Verdana, Arial, Helvetica, sans-serif">End
Date:</font></strong></td>
<td width="24%"><strong><font size="2" face="Verdana, Arial, Helvetica, sans-serif">Impressions:</font></strong></td>
</tr>
<tr>
<td bgcolor="#CCCCCC"><font size="2" face="Verdana, Arial, Helvetica, sans-serif">1</font></td>
<td><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><%=MonthName(Month(started))%></font></td>
<td><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><%=started%></font></td>
<td><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><%=lastDayOfThisMonth%></font></td>
<td><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><%=(DateDiff("D",started,lastDayOfThisMonth ) + 1)*imp_per_day%></font></td>
</tr>
<tr>
<td bgcolor="#CCCCCC"><font size="2" face="Verdana, Arial, Helvetica, sans-serif">2</font></td>
<td bgcolor="f4f4f4"><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><%=MonthName(Month(lastDayOfThisMonth+1))%> </font></td>
<td bgcolor="f4f4f4"><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><%=lastDayOfThisMonth+1%></font></td>
<td bgcolor="f4f4f4"><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><%=lastDayOfThisMonth2%></font></td>
<td bgcolor="f4f4f4"><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><%=(DateDiff("D",started,lastDayOfThisMonth 2) + 1)*imp_per_day%></font></td>
</tr>
</table></td>
</tr>
</table>
<br>
<table width="231" border="1" cellpadding="0" cellspacing="0" bordercolor="#000000" style="border-collapse: collapse">
<tr>
<td width="229">
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tr>
<td colspan="2" bgcolor="#999999"> </td>
</tr>
<tr>
<td width="14%" bgcolor="#CCCCCC"><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><strong>Start
Date:</strong></font></td>
<td width="86%" bgcolor="f4f4f4"> <input name="start" type="text" id="start2" size="10" maxlength="10">
<font size="1" face="Verdana, Arial, Helvetica, sans-serif">mmddyyy</font></td>
</tr>
<tr>
<td bgcolor="#CCCCCC"><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><strong>End
Date:</strong></font></td>
<td bgcolor="f4f4f4"> <input name="end" type="text" id="end4" size="10" maxlength="10"></td>
</tr>
<tr>
<td bgcolor="#CCCCCC"><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><strong>Impressions:</strong></font></td>
<td bgcolor="f4f4f4"> <input name="imps" type="text" id="imps" size="20" maxlength="20"></td>
</tr>
<tr align="center" bgcolor="#999999">
<td colspan="2"> <input type="submit" name="Submit" value="Submit">
</td>
</tr>
</table></td>
</tr>
</table>
</form>
</body>
</html>
Any ideas?