Originally Posted by wcrosman
If you are running a 32 bit OS then more ram will not help. 32 bit OS's cannot use much more than 3 Gig. If you've a 64 bit OS then by all means upgrade to at least 8 gig. You should see noticeable improvements.
The OS can actually use up to at least  4GB. Each process (e.g. one instance of Photoshop or Web-browser) is, however, limited to a maximum of 3GB, and in normal circumstances, that limit is actually 2GB rather than 3GB.
Having said that, if you use a 512MB graphics card, that will use up 0.5GB of the 4GB total, and there are probably the odd other card that uses a bit of memory too, so much more than 3GB becomes hard to get if you don't have more than 32 bits of addressing to work with [because the most that we can reach with a 32-bit number is 4GB].
Photo editing programs use the graphics card in very simple ways, so I doubt very much that getting a better graphics card would help much.
However, it would be useful to figure out why it is running slow. If you are very technical, you could run Intel VTune (or AMD CodeAnalyst if you have an AMD processor) on the machine and get data of precisely what is being slow. Most people aren't that technical, so I'll explain the "simple method" too: Start task manager, select the "performance tab". Look at how much processors are loaded (you'll have one "wiggly line graph" box for each processor). Are all processor cores loaded, or just the one?
Look at how much memory is being used (that's another, usually less wiggly, line diagram below the CPU load diagram).
Look at physical memory total vs. available. Look at the "commit charge" and "kernel memory".
If the CPU cores are loaded, check the "processes tab", and click on teh "CPU" heading to see which process(es) that are using much processing time.
If you feel that the above isn't enough to decipher the task manager, you can post screen shots of task manager, and someone would be able to figure out what is going on.
It would also help if you explain what part of the processing in the application you feel is slow - when you start the application, opening images, saving, adjusting levels, redrawing after zoom or other changes or whatever you feel should be faster. Also how large are the images, and how many do you load at the same time. How many layers are you working with?
 Server versions of 32-bit Windows can use up to 64GB with PAE, whilst standard XP or Vista for "home" use in 32bit mode are indeed limitied to 4GB of physical memory.
64-bit versions of the OS are capable of running as much memory as you can stuff in the machine (and thousands times more than that, it's just not possible to get big enough memory sticks and many enough slots to fill up what the processor can use).