Very quietly Microsoft has released two new patches available for the Bulldozer platform. According to the AMD blog these patches seem to offer little more then a 10% boost but the do improve over all performance. This is what Adam Kozak a product marketing manager at AMD had to say,

"Some of you may remember that AMD FX processors use a unique dual-core module architecture codenamed “Bulldozer”, which current versions of Windows® 7 were not specifically architected to utilize. In essence, for those with an AMD FX-8150 Processor, for example, Windows 7 sees the eight available cores and randomly assigns threads to them.

In initial testing of the upcoming Windows 8 operating system, we’ve seen performance improvements of up to 10% in some applications, when compared to Windows 7. This is because the system correctly recognizes the AMD FX processor architecture and cores. Thanks to close collaboration between Microsoft and AMD, Microsoft recently completed back-porting some of the Windows 8 scheduler code for AMD FX processors into a hotfix for Windows 7."
Here are the directions given by Adam Kozak,
So if you have an AMD FX processor, here’s what you can do to update your version of Windows 7:

1) Download the scheduler update (KB2645594) and install. This will tell the scheduler that your AMD FX processor contains dual-core modules (in fact this is similar to the SMT path that the other guys use). In essence, threads 1-4 now get assigned to their own module first.

2) Download the core parking scheduler update (KB2646060) and install. This will prevent Windows 7 shutting down unused cores prematurely when there are threads to be assigned (there’s a performance penalty parking and then un-parking a core).

The best possible cases for improvement are applications that use ½ cores in your AMD FX processor. In our testing using the AMD FX-8150 processor, we found the best improvement in wPrime, Left 4 Dead 2, and Lost Planet. Below you’ll find links to the patches:

Patch 1
Patch 2

Source: AMD Blog