The manual way…..
<select name="interest">
<option value="seo"<?php if($result['interest'] == 'seo'): ?> selected="selected"<?php endif; ?>>SEO и Блоговодство</option>
.....
The better way would be to loop through the interests
$interests = array(
'seo' => 'SEO и Блоговодство',
'auto' => 'Авто',
....
);
<select name="interest">
<?php foreach( $interests as $var => $interest ): ?>
<option value="<?php echo $var ?>"<?php if( $var == $result['interest'] ): ?> selected="selected"<?php endif; ?>><?php echo $interest ?></option>
<?php endforeach; ?>
</select>