You can use CompareValidator for the date type & RangeValidator for the
range. Example:
<asp:CompareValidator id="CompareValidator1" runat="server"
ErrorMessage="CompareValidator" Type="Date"
ControlToValidate="TextBox1"
Operator="DataTypeCheck">
<asp:RangeValidator id="RangeValidator1" runat="server"
ErrorMessage="RangeValidator" MaximumValue="2011-01-01"
MinimumValue="2009-01-01"
ControlToValidate="TextBox1">RangeValidator
<asp:TextBox id="TextBox1" runat="server">
Set the minimum value on page load.