A: 

This is quick a cut/paste from a code I used for a client whose attribute was a dropdown-type attribute.

Your attribute code must be "platform" for this to work.

<?
 $product = Mage::getModel('catalog/product');
 $attributes = Mage::getResourceModel('eav/entity_attribute_collection')
         ->setEntityTypeFilter($product->getResource()->getTypeId())
         ->addFieldToFilter('attribute_code', 'platform');
 $attribute = $attributes->getFirstItem()->setEntity($product->getResource());
 $_platforms = $attribute->getSource()->getAllOptions(false);
 ?>
<select onchange="location.href='<?php echo $this->getUrl('catalogsearch/advanced/result') . '?platform[]='; ?>'+this.value;">
   <option selected><?php echo $this->__('Search by platform') ?></option>
    <?php foreach($_platforms as $_platform) : ?>
   <option value="<?php echo $_platform['value']; ?>"><?php echo $_platform['label']; ?></option>
    <?php endforeach; ?>
  </select>
vrnet
Thanks I already figured it out. Just changed name="name" to name="q" and it worked.May be a couple of other changes but now it works.
Ali
Ok. "q" is used for standard search (not avanced) and thus doesn't allow you to use precise attributes.ie : if you are selling computers with differents operating systems and want to perform a search based on the OS, if you use "q" the result will list all products mentionning the string in the query (let's say Ubuntu). So, if you also sell keyboard and have something like "compatible with Ubuntu" in its description, your search result will also list the keyboard. Whereas, if you use the advanced search method using the "platform" attribute, the keyboard won't be listed.
vrnet