InfoPath Percentage Symbol Field

This applies to InfoPath 2007 as well.

That's just wrong:

Note Microsoft Office InfoPath 2003 does not add percent symbols to numbers that are formatted as percentages. To add a percent symbol to a control's label, click where you want the percent symbol to appear, and then type %.

http://office.microsoft.com/en-us/infopath/HP010938331033.aspx