Také jde dát všemu left a doštelovat marginem

<div style="width: 330px">
<input style="width: 100px; float: left" 
type='button' value='Vlevo' onClick = "location.href = 'stranka'">

<input style="width: 100px; margin: 0 10px; float: left" 
type='button' value='Uprostřed' onClick = "location.href = 'stranka'">

<input style="width: 100px; float: left"
type='button' value='Vpravo' onClick = "location.href = 'stranka'">
</div>