Since I bought a camera producing RAW images and became more adventurous with Photoshop, I have outrun the capacity of my old PC, although it has 4GB of memory. Most of the available quad-core machines seem to be designed for gamers, which is not what I require. Martin McNicol
Almost any modern dual-core PC should be fine for Photoshop, which uses up to 2GB of memory on 32-bit systems, and mainly does two-dimensional graphics. You don't need a gaming machine designed to provide high frame rates with 3D graphics.
For good performance with Photoshop, it's best to have a fast processor and a very fast hard drive, although a fast 2D graphics card should help. Moving to a 64-bit version of Windows XP or Vista (or Mac OS 10.5) would also speed up the program in use, but you might have a few problems getting drivers for peripherals. Sadly, even the latest Adobe Creative Suite 3 is still 32-bit, and the major benefits will not emerge until it's a 64-bit application, and has been optimised for multi-core processors.
Adobe has a technical note, Optimise performance of Photoshop (CS2 on Windows) at tinyurl.com/2rvjs2. Following Adobe's advice could speed things up a bit, and therefore make your need for a new PC less urgent.