This will vary depending on the Product Type. For Product General the layout of the product page is set in

\includes\templates\YOUR_TEMPLATE\templates\tpl_product_info_display.php

You can move this section about to alter the position of attributes:

Code:
<!--bof Attributes Module -->
....
<!--eof Attributes Module -->
To fine tune the position of the attribute block, or individual attributes, with CSS look in this file for the relevant HTML code:

\includes\templates\YOUR_TEMPLATE\templates\tpl_modules_attributes.php