It seems the preview for IE10 release by Microsoft last week will only work on Windows 7 (32-bit or 64-bit) and the future Windows 8. Microsoft has already shut-out Windows XP users from IE9, so now they are following suit with Vista and the future IE10. The good news here is Firefox 5 (due out in late June) will continue to support Windows Vista and (far as I know) Windows XP. Source: Seattle PI: Microsoft Blog