hi,
try right clicking on teh installer. go to properties. then click compatability, run for win xp sp2. then go to bottom ofg the page and click on run as administrator. this should clear up the problem. i'm still using the beta version of vista and it works just fine this way. you may have to right click the desk icon and do the same thing there as well. and you can re-install with the new compatability selections without uninstalling first.