From w3: The label itself may be positioned before or after or around the associated control.
<label for="lastname">Last Name</label>
<input type="text" id="lastname" />
or
<input type="text" id="lastname" />
<label for="lastname">Last Name</label>
or
<label>
<INPUT type="text" name="lastname">
Last Name
</label>
Note that the third technique cannot be used when a table is being used for layout, with the label in one cell and its associated form field in another cell.
Either one is valid. I like to use either the first or second example, as it gives you more style control.