Adobe's new Photoshop CS4 packs a ton of fresh features and an updated interface, which alone make it a worthy upgrade for existing users.

But the big news is that Photoshop now comes in both 32- and 64- bit windows vista versions. the 64-bit edition will allow PC's with lots of RAM to work on very large images with less hard-disk swapping, thus speeding up operations. with shrinking amount of RAM available to modern PC's(due to a 4GB limit on 32-bit windows versions and those operating system's increasing hunger for RAM).

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I tested betas of both the 32 and 64 bit versions of Photoshop CS4 by installing them on a workstation with dual intel Xeon CPU's, running windows vista 64-bit and 8GB of RAM. Photoshop requires that you manually allocate a specific amount of RAM to it , rather that its acquring the RAM on the fly, i was able to set the 64-bit version to take up 6879MB of RAM, and to set the 32-bit version to comsume 3185 of RAM. the amounts will vary depending on your system, especially your graphics card.

Running the 64-bit version will provide little performance benfit other than the ability to adress more RAM. And even a system with lots of RAM won't be able to avoid reading and writing data to your hard disk a process that still proves time consuming. I got to watch a dialog box for a coffee break-length period when i asked Photoshop to apply a simple momochrome gradient to my 5.6GB file.