Am I doing this correctly? It works, just want to know if there are better ways of doing it.

<apex:pageBlockSection id="pageblock1" title="PageBlock" columns="2" rendered="{!object.field__c==true}">                
	<apex:pageBlockSectionItem id="id1" helpText="{!$ObjectType.object__c.Fields.field__c.inlineHelpText}">
	 <apex:outputLabel value="This is a long field label" for="field1" />
	  <apex:inputField id="field1" value="{!object.field1__c}" >                    
		<apex:actionSupport event="onchange" action="{!saveobject}" rerender="pageblock1" />                     
		<!-- Start Error outputPanels -->
			<!-- Check for Null -->
			   <apex:outputPanel rendered="{!object.field1__c != 'Yes' && object.field1__c != 'No'}">
			 <div class="errorMsg"><strong>Error:</strong>&nbsp;You have to select a value.</div>
			   </apex:outputPanel> 
			<!-- Other Criteria-->                   
			   <apex:outputPanel rendered="{!object.field1__c == 'No'}">
			 <div class="errorMsg"><strong>Error:</strong>&nbsp;Requires "Yes" to generate Proposal</div>
			   </apex:outputPanel>
		<!--End Error outputPanels -->                                
	  </apex:inputField>           
	</apex:pageBlockSectionItem>  
</apex:pageBlockSection>