Photoshop CS5 is now capable of running in native 64-bit on both Mac and Windows. This means Photoshop can now address hundreds of gigs of RAM (instead of just 4 GB). The results are speedier operations—the bigger the file, the bigger the difference. The 32-bit version is on the same disc, so if your third-party plug-ins haven’t been updated yet, you can run Photoshop in 32-bit.
Adobe Photoshop CS5
By Bryan O’Neil Hughes