1. Hardware incompatibilities

It's no huge surprise to anyone that the upgrade to Windows Vista has created numerous instances of driver incompatibility and dissatisfaction - these kinds of issues arise whenever there's a major operating system upgrade. What has been surprising is the frustrations gamers have experienced in getting their existing hardware - 3D graphics cards and the like - to work with their existing games library in Windows Vista at the same performance levels as in Windows XP. The internet is rife with reports of games such as World of Warcraft and F.E.A.R. running at 20 percent to 40 percent slower frame rates.

Not surprisingly, the chief culprit is 3D card drivers, particularly for DirectX 9 (DX9) and lower-calibre video cards. (DirectX is a Windows API designed by Microsoft to allow software developers standardized low-level access to PC peripherals such as the video graphics processor. The newest version is DirectX 10.)

Windows Vista includes a new driver model that taps the graphics processing unit (GPU) to perform memory scheduling, which is useful for allocating memory and other system resources to each open application. The operating system also uses the GPU to create and maintain multiple instances of 3D graphics use at both the interface and application levels. As an example, each open window in Vista - be it a folder, game, or otherwise - is considered a separate application, and the graphics involved in displaying this application are controlled by the GPU.

With Windows XP, the operating system itself, not the GPU, performed these functions. More specifically, drivers for XP were written to and resided in kernel mode - the base layer of Windows. In order to allow the GPU to maintain the aforementioned instances of 3D applications, on the other hand, drivers for Windows Vista operate at a more localized layer of the operating system known as user mode.

The good news is that this architecture shift should result in increased stability under Vista. Because the driver is localised and exists in multiple instances, a crash that’s caused by or otherwise affects the graphics driver will have no adverse impact on other 3D applications.

The bad news is that it's going to take time for developers to figure out the most effective way to write drivers for this new model. Today's performance slowdowns are largely a result of driver developers having to relearn the delicate process of writing the most efficient code for graphics processors.

Unless you want to roll your system back to Windows XP, the simple answer to this problem is to keep updating your video card drivers - graphics card manufacturers ATI (now owned by AMD) and nVidia are constantly releasing new and improved drivers. Thankfully, with each driver iteration released by the companies, gaming performance for DX9 cards in Windows Vista has improved. In another few months, it's highly likely this will be a non-issue. In the meantime, however, gamers will suffer.

2. Backward incompatibility

One of the biggest frustrations for any gamer when there's an operating system upgrade is the hard fact that some older games simply will not work in the new environment. For example, the upgrade from Windows 98/ME to Windows XP in 2002 proved devastating for this reporter. My old favourite, High Heat Baseball, a game that had received hundreds of hours of play, simply would not work under any circumstances.

The same frustration is occurring in large doses for gamers who have transitioned to Windows Vista. Chris Donahue, Microsoft's director of Windows graphics and gaming technologies, said that the software giant had tested the 1,000 most popular PC games over the last five years on a variety of hardware configurations in the Vista environment. That's a good start, but given the wide variety of PC games on the planet, it's only a small dent.

For what it's worth, Donahue also noted that Windows Vista is way ahead of where Windows XP was in the same time frame in terms of graphics performance and backward compatibility. Unfortunately, this is small consolation for gamers who can't get their favourite titles to work properly.

One of the biggest complicating factors in getting legacy XP games to work in Windows Vista is the new operating system's User Account Control functionality. This new security feature forces users to work using restricted ‘standard’ accounts, as opposed to defaulting to all-powerful ‘admin’ accounts. According to Donahue, the resulting new model for installing applications and files in write-protected directories is one of the biggest sources of backward incompatibility. The answer is to specify another directory - one that a standard user account can write to - rather than the Program Files folder when installing games.

One other source of backward incompatibility appears to be caused by the StarForce copy-protection schemes that many game makers have incorporated into their titles. Older versions of this popular form of antipiracy software have reportedly caused a number of errors that have prevented gamers from playing their favourite Windows XP games. The cause? Simple incompatibility - like many applications, old versions of StarForce don't work properly in Vista environments. StarForce recently released a new version of its software that’s certified to be compatible with Vista; unfortunately, the only way to get it is to download a patch for your particular game from the game publisher's site.

As a general (if obvious) rule, you should download and install any available updates for your games before running them. Many developers and publishers have released patches that increase compatibility with Vista.

One final note: For an excellent breakdown of how well the most popular games operate with Windows Vista, see ExtremeTech's Will Vista Run Your Games?

3. Lack of DirectX 10 games

Incompatibilities are awful, but perhaps the greatest flaw with Vista gaming is the fact that, as of March 2007, not a single DirectX 10 game has been released. And none are close to being released. The sad truth for gamers is that it will take at least six months for Windows game developers to finish the DX10 titles that are currently under development. Crysis is one of the titles gamers are most excited about, but it's not scheduled for release until late 2007.

This means that during this half-year waiting period, there really isn't any reason for gamers to switch to Windows Vista. However, users with DX10 video cards such as nVidia's GeForce 8800 GTX or GTS may experience gaming satisfaction with older games on the new operating system. Microsoft and numerous outlets have indicated that DX10 video cards have provided nice performance boosts for DX9 video games. Our tests have confirmed this, showing frame rate boosts in F.E.A.R. and Supreme Commander.

Windows Vista gaming guide

Six reasons why Vista is good for gaming

Vista: Should gamers upgrade?

See PC Advisor's definitive Windows Vista review.