That isn't correct. Like Ajajajak said, floated elements are taken out of the normal document flow.
Your img element doesn't sit next to your div because div elements are block-level elements and as such these are laid out vertically by default rather than horizontally (inline-level elements).
Thus when you place your div element before your img element, which is an inline element, the latter will still be placed below your div, as a block-level element fills its parent's content area and can't have other block or inline elements at its sides, unless you float them.
So, if you didn't want to float your div, you could set display:inline on your div rather than on the img (as it's inline anyway), thus generating an inline box in CSS and making your img sit next to your div.
/* GELIJKVLOERS */
margin: 10px 0 0 0;
padding: 0 0 0 8px;
border: 1px solid #000;