how to Retaining selected value of checkboxes in postback form in php

Dear Friends,
I have this simple form

<table  align="left" cellpadding="3" cellspacing="0" width="550" border="0">
          <form action="" name="WebToLeadForm" method="post" id="WebToLeadForm" onsubmit="javascript: return form_validation();">

<tr>
                <td colspan="2" ><strong>What digital printing equipment do you have? </strong></td>
              </tr>
              <tr>
                <td >HP: </td>
                <td ><input id="printerhp_c" name="printerhp_c" type="checkbox" value="HP" value="<?php echo htmlentities($hp) ?>" />
                </td>
              </tr>
              <tr>
                <td >Xerox: </td>
                <td ><input id="printerxerox_c" name="printerxerox_c" type="checkbox" value="Xerox" value="<?php echo htmlentities($xerox) ?>" />
                </td>
              </tr>
              <tr>
                <td >Konica Minolta: </td>
                <td style="font-weight: normal;"><input id="printer_konicam_c" name="printer_konicam_c" type="checkbox" value="Konica Minolta" value="<?php echo htmlentities($km) ?>"/>
                </td>
              </tr>
              <tr>
                <td >Canon: </td>
                <td ><input id="printercanon_c" name="printercanon_c" type="checkbox" value="Canon"  value="<?php echo htmlentities($canon) ?>" />
                </td>
              </tr>
              <tr>
                <td >Kodak<span sugar="slot">: </span></td>
                <td ><input id="printerkodak_c" name="printerkodak_c" type="checkbox" value="Kodak"  value="<?php echo htmlentities($kodak) ?>"/>
                </td>
              </tr>
              <tr>
                <td >Ricoh: </td>
                <td ><input id="printerricoh_c" name="printerricoh_c" type="checkbox" value="Ricoh"  value="<?php echo htmlentities($ricoh) ?>" />
                </td>
              </tr>
              <tr>
                <td >Oc&eacute;: </td>
                <td ><input id="printeroce_c" name="printeroce_c" type="checkbox" value="Océ"   value="<?php echo htmlentities($oce) ?>"/>
                </td>
              </tr>
              <tr>
                <td >Other: </td>
                <td ><input id="printerother_c" name="printerother_c" type="checkbox" value="Other"  value="<?php echo htmlentities($other) ?>" />
                </td>
              </tr>

</form>


I just want that when i submit the form and code went wrong and page refresh/redirect all checkbox remain checked.

Thannks in
advance.
With Regards
Rajesh

Tags: PHP