How many version of Microsoft offering Win7

Deserved or not, Microsoft had dug itself a cool, deep, dark hole with Windows Vista. Users demanding that Redmond extend the life of Windows XP weren’t exactly something they could be proud of, either. Bombarded by complaint and negative press even after the first service pack was released, the bar had been set high for Vista's successor: Windows 7. This evaluation is based on an official copy of the Windows 7 RTM that Microsoft provided to CNET on July 30, 2009.
Luckily for Microsoft, Windows 7 is more than just turn. As buggy and irritating as Vista was, Windows 7 isn't. Instead, it's the successor to Windows XP that Microsoft wishes Vista had been, and finally chairs it on competitive footing with other major operating systems like OS X and Linux.
Microsoft is offering six versions of Windows 7: Starter, Home Premium, Professional, Ultimate, OEM, and Enterprise. Windows 7 will support both 32-bit and 64-bit systems. The bare minimum requirements for the 32-bit include a 1GHz processor, 1GB RAM, 16GB available hard-disk space, and a DirectX 9 graphics device with WDDM 1.0 or higher driver. A touch-screen monitor is required to take advantage of the native touch features. Do note that some users have claimed to have limited success running the Windows 7 beta with less than 1GB of RAM, but that's not recommended.
Installation
Microsoft is offering several paths to install Windows 7. People can buy a new computer with the operating system already installed, upgrade from Windows XP or Vista, or do a clean install on a computer the user already owns. The upgrade modus operandi is different depending on whether you're running Windows XP or Windows Vista. Both XP Home and XP Pro users will have to back up their data, then choose Custom from the install disc. Custom will have the same effect as a clean install, although it'll save your old data in a folder called Windows.old. If you're not sure if your current computer can run Windows 7, you can download and run the Windows 7 Upgrade Advisor from Microsoft.
Features: Taskbar and Aero Peek
It features pinned programs using large, easy-to-see icons. Mouse over one and all windows associated with that program appear in preview. Hover over the preview to show a full-size preview of the program, or click on the window to bring it to the front. Jump lists are an additional new taskbar improvement that make recently opened documents easier to get to. If you've noticed the missing Show Desktop icon, that's because it's been baked into the taskbar itself. Mouse over to the right corner. Click on the box to minimize all your programs.