It's hard to keep the details straight when discussing Microsoft's next version of its client operating system (OS). But given some recent announcements, we thought we'd give an update of the current landscape for anyone who hasn't updated their Vista fact and trivia spreadsheet.

You should know that:

• Longhorn is Vista and Vista is the new XP. The history of Vista is really the history of Longhorn, the former code-name for the operating system update. But last summer, Microsoft announced that the name Longhorn was history, and Vista was in. Over time, as Longhorn morphed into Vista, some of the more advanced features were delayed, most notably an enhancement to the NTFS file system called WinFS. Once branded Vista, the OS feature set has remained relatively stable.
  
  
• It will arrive in late fall for businesses, early 2007 for consumers. Despite earning billions and employing tens of thousands, Microsoft is having a tough time getting Vista ready for release. The vendor's software release dates are moving goal posts and subject to continual revision, but here's that the latest word:
  
  "Microsoft is on track to complete the product this year, with business availability in November 2006 and broad consumer availability in January 2007."
  
  
  
  
• The most noticeable change for users will be the new interface. Underneath the hood, Vista will offer many new features, particularly around securing the OS (for example, requiring an administrator password to install new software). Other changes, such as improved media handling and an update to the Web browser will also be part of the package. However, the user interface (UI) changes will be the most obvious for current Windows users. Depending on the hardware of a PC (specifically, its graphics card), the UI will offer more eye candy, such as window translucency and 3D transformations. The high-end interface "experience" is called Windows Aero.
  
  
• It will come in six flavors. In late February, Microsoft announced that Vista will ship in many configurations. There are versions for businesses, consumers, and a stripped down version for some targeted markets. Microsoft has not yet delivered a simple table of features for each version, so the features outlined in a specific press release, executive interview, or product overview may vary, be unclear, and will be subject to final revision. The following details have been taken from the most recent official press and site materials.
  
  Windows Vista Business and Windows Vista Enterprise are what most businees users will eventually experience at work. The former is the basic OS for organizations, and includes some components, like support for Tablet PCs, that were previously offered in special versions of Windows. The latter edition adds some additional features, such as stronger hard drive encryption and the ability to run UNIX programs.
  
  Consumers will have a choice of three configurations. Windows Vista Home Basic is for bare bones home computing and does not include new features, including the full blown Aero UI experience. Most consumers will find they will want Windows Vista Home Premium, which adds features like enhanced systemwide search, Media Center capabilities, and the ability to burn DVDs. Finally, there's Windows Vista Ultimate, which includes all the features of the corporate and consumer versions. Consumer versions of the OS are supposed to ship with all of the Ultimate feature set -- consumers will be able to unlock the features for a price.
  
  Finally, there is Windows Vista Starter, designed for low end computers sold in the developing parts of the world. Starter-equipped PCs are primarily designed to counter piracy and the spread of Linux-based alternatives.
  
  All of the editions except for Starter will come in either 32- or 64-bit versions, so there will end up being 11 distinct code bases in the wild.
  
  
• If not delayed further, Windows will launch five years and a month after XP . Microsoft officially announced the Windows XP client OS in October of 2001. The software came in only two flavors, Windows XP Professional and Windows XP Home Edition. A year later, Windows XP Media Center Edition was officially released. For trivia buffs, Windows 3.0 came out in May 1990, Windows 95 was released in August 1995, and Windows 2000 made its official debut in February 2000.
  
  
• It should provide significantly more security and protection from hackers than XP. As mentioned above, a key new feature of Vista will be the way it limits access to core components. In addition, the OS enhances the existing automatic updating and patching of XP. An improved firewall is deigned to further secure the software, while the Windows Defender component will attempt to thwart attacks from spyware and other malicious software.
  
  Out of the box, Vista alone won't deliver the ultimate in Microsoft protection for a consumer PC, though. For an additional cost, the vendor will provide Windows OneCare Live, a souped up protective service that includes features like backup software and additional access to help. OneCare is currently priced at $49.95 a year for up to three Windows PCs.

While the name Vista is sure to stay, the launch date and feature set may change. One thing remains unclear: Why has it taken Microsoft so long to get Vista out the door?

Obviously, the changes and enhancements of the OS code are complex, and the need to ensure it can function on a huge variety of desktops and notebooks means that Microsoft must take its time. But while we will eventually congratulate the company if Vista can accomplish its most important task -- dramatically increasing the security and reliability of Windows -- we certainly won't give the company a thumbs up for its ability to deliver a timely update to its flagship offering. No matter when Vista gets out the door, it's downright embarrassing that Microsoft has taken this long to get the job done.