While Microsoft plans to offer $39.99 digital upgrades for Windows 8 Pro, a physical copy will set you back bit more. $69.99 is the suggested retail price for the full package, but Amazon is essentially cancelling out the difference for those who pre-order by throwing in $30 of promotional credit that can be used throughout its online store. There are some exceptions: you won't be able to put the bonus cash toward digital items like Kindle ebooks, MP3s, and videos. But if you're a frequent Amazon shopper, we doubt you'll have much trouble putting it towards something on that growing wish list. You'll receive the $30 credit via email 30 days after your boxed copy of Windows 8 ships. The pre-order promotion also extends to Windows 8 Pro Pack for those that might want to bump their regular edition of Microsoft's desktop OS to the more feature-rich version later. Windows 8 will be released on October 26th.

Update: Sorry, folks. Despite offering this deal for several hours, it seems Amazon has abruptly pulled the option to pre-order the $69.99 upgrade version of Windows 8. Instead it's now pointing shoppers to a reseller which lists the upgrade at a much higher $159.99.