I was 'rolling' my own SOAP messages (for use in .asp pages).  However I noticed today that the format in which data is returned as suddenly changed (see parts in bold)!

Old Format:

<?xml version="1.0" encoding="UTF-8"?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
 <soapenv:Body>
  <queryResponse xmlns="urn:partner.soap.sforce.com">
   <result>
    <done>true</done>
    <queryLocator xsi:nil="true"/>
    <records>
     <ns1:type xmlns:ns1="urn:sobject.partner.soap.sforce.com">Lead</ns1:type>
     <ns2:Id xmlns:ns2="urn:sobject.partner.soap.sforce.com">LEADIDHERE</ns2:Id>
    </records>
    <records>
     <ns3:type xmlns:ns3="urn:sobject.partner.soap.sforce.com">Lead</ns3:type>
     <ns4:Id xmlns:ns4="urn:sobject.partner.soap.sforce.com">2NDLEADIDHERE</ns4:Id>
    </records>
    <size>2</size>
   </result>
  </queryResponse>
 </soapenv:Body>
</soapenv:Envelope>

New Format:

<SOAPENV:ENVELOPE XMLNS:SOAPENV="http://schemas.xmlsoap.org/soap/envelope/" XMLNS:XSD="http://www.w3.org/2001/XMLSchema" XMLNS:XSI="http://www.w3.org/2001/XMLSchema-instance">
    <SOAPENV:BODY>
        <QUERYRESPONSE XMLNS="urn:partner.soap.sforce.com">
            <RESULT>
                <DONE>true</DONE>
                <QUERYLOCATOR XSI:NIL="true"></QUERYLOCATOR>

                <RECORDS XMLNS:SF="urn:sobject.partner.soap.sforce.com" XSI:TYPE="sf:sObject">
                    <SF:TYPE>Lead</SF:TYPE>
                    <SF:ID>LEADIDHERE</SF:ID>
                </RECORDS>
                <RECORDS XMLNS:SF="urn:sobject.partner.soap.sforce.com" XSI:TYPE="sf:sObject">
                    <SF:TYPE>Lead</SF:TYPE>
                    <SF:ID>2NDLEADIDHERE</SF:ID>
                </RECORDS>
                <SIZE>2</SIZE>
            </RESULT>
        </QUERYRESPONSE>
    </SOAPENV:BODY>
</SOAPENV:ENVELOPE>

I'm assuming this is part of the Spring '04 release.  Is there a way that I can use an older version (perhaps specify the version in the request message)?  Or will I need to update my processing everytime that a change is made on Salesforce.com???