Formatting display of XML decimal fiend in excel 2007

Is it possible to control how a decimal type is displayed in excel 2007?  I have been trying to modify the element declaration to no avail.  I want to always display two digits after the decimal point.  It works when the number contains digits after the decimal point, but excel will not display a value like 7.00 (it displays 7 instead), even if that value exists in my xml data.  Here is an example of my .XSD information:

       <element name="Amount">
        <simpleType>        
         <restriction base="decimal">
          <totalDigits value ="7"/>
          <fractionDigits value="2" fixed="true"/>
         </restriction>
        </simpleType>
       </element>

I don't recognize these elements as valid for Excel.I have a detailed blog/screen-cast about how to use styles for formatting. Perhaps that will help.