Yeah this is good, but the thing to keep in mind is that an OS release always drives these numbers way up. IE8 comes with Windows 7. Vista didn't do so well so the IE7 numbers reflect that.

IE9 Won't benefit from being part of an OS release (unfortunately).

It's not just that... large corporations that are sticking with XP are finally getting around to upgrading from IE6 - and skipping directly to IE8.

Windows XP Pro price raised (on average) to around $150. Windows 7 Pro is (on average) $85. I know large corporations get killer deals, but over time the cost will outweigh the benefits. I think the phase out will be less than 5 years for most businesses.