read this XML tutorials , its simple intro and will guide you http://www.w3schools.com/xml/default.asp

show your code ?

it work fine here , on firefox and IE 7 ,
but am gonna tell you advice , design your pages on Firefox first and it must work good on IE because Firefox uses web standard .
plus the most problems...

i don't get what do you mean ?
you are using sql , or some sorta of database or what ?? what is ( category also called (test) ) ?

well , i see its better for you to use <div> tags in all your codes , ( put the outer box in div , and the inner box div and deal with them )