<!--[if lt IE 8]> 
<style>
/* IE6 */
*html input.button{
  overflow: visible; /* remove padding from left/right */
  width:0;  /*remove the remaining space in IE6*/
}

/* IE7 */
*:first-child+html input.button{
  overflow: visible; /* remove padding from left/right */
  width:auto !important;
}
</style>
<![endif]-->

<input class="button" type="submit" value="IE567 sux" />

<!--[if lt IE 8]> 
<style>
input.button{
  overflow: visible; /* remove padding from left/right */
  width:auto; /* remove the remaining whitespace in IE7 */
  _width:0;  /*remove the remaining space in IE6*/
}
</style>
<![endif]-->

<input class="button" type="submit" value="IE567 sux" />

To remove that ugly added padding from submit buttons try this
width:auto !important; seems to work for IE7

IE  fix for ugly padding on left and right of submit buttons

ie, button, ie6

CSS