horizontally aligning form elements

is there a better way to align a text input type and an submit image button (non CSS) form element besides using floats?

I need to align:

<div class="form-item" id="edit-search-theme-form-1-wrapper"> 
 <label for="edit-search-theme-form-1">Search this site: </label> 
 <input type="text" maxlength="128" name="search_theme_form" id="edit-search-theme-form-1" size="15" value="" title="Enter the terms you wish to search for." class="form-text" /> 
</div> 
<input type="image" name="op" value="Search" id="edit-submit-1"  class="form-submit Button" src="images/searchbutton.gif"  /> 

Code (markup):

 

Why would you want it better than floats? These line up automatically