its the default Kernel program , which makes it run like that, how can you change it manually, not possible... i think this makes it much easier to surf... the thing is that in XP IE6 performs better, then IE7, if IE8 comes up then also IE7 will be a better performer in VISTA, because Vista Kernel is programmed according to IE7 and IE (next ver) will be coming as an update,
in IE7 there was a great turn over, but IE6 was just an regular update to IE5,,,
you cant change it... the way it works