In the past, Macs were sometimes argued to be better for image editing than Windows-based PCs. To be perfectly honest, I'm not sure if this was true or a complete myth, but it looks like things may not be like that anymore with the introduction of Adobe's Windows-only 64-bit version of Photoshop Creative Suite 4. Until now, Adobe has strived to ensure that both the Windows and Mac versions of Photoshop come with similar features. However, due to a choice by Apple not to make the Carbon technology that is used to develop Photoshop available as 64-bit, Adobe has decided it will not be providing a 64-bit version of CS4. Adobe's product manager for Photoshop, John Nack, said:

We're not going to ship 64-bit native for Mac with CS4. We respect Apple's need to balance their resources and make decisions right for that platform. But it does have an impact on developers.

Adobe's preliminary testing suggests that the 64-bit version of Photoshop CS4 will offer a performance boost of 8-12%, with the benefits being much greater for memory-intensive tasks due to its ability to take advantage of more than 4GB of memory.