Mac OS X Leopard will cost $29. Only the server version has a different price. By my count, Microsoft’s Windows 7 has about 10 different price tags, depending on the version.

Unlike Vista, every edition of Windows 7 is a superset of the previous edition, so you will not lose any features when upgrading. Once you have some edition of Windows 7 on your system, whether you purchased it via an OEM or just upgraded from Windows XP or Windows Vista, you will be able to upgrade to a “more premium” version of Windows 7 by purchasing an upgrade key to unlock additional features, just as with Vista.

US prices range from $50 to $320. $50? Yes, Windows 7 retails for $50 through July 11, 2009 or while supplies last. The money you save can be used on anti-virus and spyware software.