As we reported earlier this morning, major online retailers including Amazon.com, Staples, and Office Depot have started accepting pre-orders for Windows 8 software and machines powered by Windows 8. Now that Windows 8 is up for pre-order, you might be considering to reserve your Windows 8 full version or upgrade copy. Windows 8 upgrade copy (packaged DVD) is available for $69.99 for existing Windows XP, Vista, and Windows 7 users. If you’re planning to pre-order your XP, Vista, or Windows 7 to Windows 8 upgrade copy, you can head over to this page of Amazon.com to get $10 off on Windows 8 software, meaning that customers can pre-order the upgrade copy for $59.99 instead of the normal $69.99. You need to enter the promotional code “WINDOWS8” on the Review Order page to avail the offer. Please note that this promotional code is limited to one per customer and is valid till October 14, 2012 only. Existing Windows users running Windows XP, Vista and Windows 7 can upgrade to Windows 8 for just $39.99 via Windows.com using Windows 8 Upgrade Assistant. Online upgrade to Windows 8 will be available starting from October 26, 2012. As you might already know, Windows 7 users will be able to keep everything from personal files to installed programs during the upgrade. While Vista users will be able bring along personal file and Windows settings, Windows XP users can keep only personal personal files. If you want to test drive Windows 8 RTM before pre-ordering your copy, visit to this page to download 90-day trial version of Windows 8 RTM Enterprise edition.