ein paar Sachen korrigiert, das Problem bleibt aber, dass die Labels nicht umbrechen.
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>TEST</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
<style type="text/css">
form { width: 100%; min-width: 300px; background-color:silver;}
fieldset { float: left; border: none; }
fieldset.spalte1 { margin: 10px; padding-right:10px; border-right:1px solid black; min-width:200px;}
fieldset.spalte2 { margin: 10px; min-width:300px;}
fieldset label {color:red; min-width:200px; display: block;}
fieldset img {display: block;}
fieldset input {display: block;}
form .formfooter { clear:both; margin: 10px; }
</style>
</head>
<body>
<form action='#'>
<fieldset class="spalte1">
<label for="f1">F1 lange Beschriftung lange Beschriftung lange Beschriftung lange Beschriftung lange Beschriftung lange Beschriftung :</label>
<input type="text" id="f1" name="f1" size="50"/>
</fieldset>
<fieldset class="spalte2">
<label for='bild'>Bild trallala trallala trallala trallala trallala trallala trallala trallala trallala trallala trallala trallala trallala trallala trallala tralla:</label>
<input name="bild" id='bild' type="file" size="50" maxlength="100000" accept="text/*"/>
<img src='/images/nologo.gif' alt='alt'/>
<label for="f11">F11:</label>
<input type="text" id="f11" name="f11" size="40" />
</fieldset>
<div class="formfooter ">
<hr/>
<input type="submit" value="absenden" name="ok" />
</div>
</form>
</body>
</html>