Upgrading to Windows 8: What you need to know (FAQ) | Windows 8 - CNET Reviews

"For PCs with the above operating systems purchased prior to June 2, 2012, you can download the upgrade from Microsoft for $39.99. For new, non-Windows 8 PCs purchased between June 2 and January 31, 2013, Microsoft will offer the Windows 8 Pro upgrade download for $14.99 (presumably to help prevent a pre-Windows 8 drop-off in new PC purchases)."

" You can buy the boxed version of the Windows 8 Pro upgrade for $69.99. If you purchase the downloadable upgrade, Microsoft will offer you the option to purchase a DVD version for an additional $15. The upgrade installation process will also offer you the ability to burn a DVD or make a bootable USB key using your own media, for no charge.