The third quarter of 2008 was the first time when worldwide notebook PC shipments exceeded desktops, with 38.6 million units versus 38.5 million units. The sales breakdown of the Apple Macintosh has seen sales of desktop Macs staying mostly constant while being surpassed by that of Mac notebooks whose sales rate has grown considerably; seven out of ten Macs sold were laptops in 2009, a ratio projected to rise to three out of four by 2010. The change in sales of form factors is due to the desktop iMac moving from affordable (iMac G3) to upscale (iMac G4) and subsequent releases are considered premium all-in-ones. By contrast, the MSRP of the MacBook laptop lines have dropped through successive generations such that the MacBook Air and MacBook Pro constitute the lowest price of entry to a Mac, with the exception of the even more inexpensive Mac Mini (albeit without a monitor and keyboard), not surprisingly the MacBooks are the top-selling form factors of the Macintosh platform today. The decades of development mean that most people already own desktop computers that meet their needs and have no need of buying a new one merely to keep pace with advancing technology. Notably, the successive release of new versions of Windows (Windows 95, 98, XP, Vista, 7, 8, 10 and so on) had been drivers for the replacement of PCs in the 1990s, but this slowed in the 2000s due to the poor reception of Windows Vista over Windows XP. Recently, some analysts have suggested that Windows 8 has actually hurt sales of PCs in 2012, as businesses have decided to stick with Windows 7 rather than upgrade. Some suggested that Microsoft has acknowledged "implicitly ringing the desktop PC death knell" as Windows 8 offers little upgrade in desktop PC functionality over Windows 7; instead, Windows 8's innovations are mostly on the mobile side. The post-PC trend has seen a decline in the sales of desktop and laptop PCs. The decline has been attributed to increased power and applications of alternative computing devices, namely smartphones and tablet computers. Although most people exclusively use their smartphones and tablets for more basic tasks such as social media and casual gaming, these devices have in many instances replaced a second or third PC in the household that would have performed these tasks, though most families still retain a powerful PC for serious work. Among PC form factors, desktops remain a staple in the enterprise market but have lost popularity among home buyers. PC makers and electronics retailers have responded by investing their engineering and marketing resources towards laptops (initially netbooks in the late 2000s, and then the higher-performance Ultrabooks from 2011 onwards), which manufacturers believe have more potential to revive the PC market than desktops.