It seems that the new PS CS3 patch has changed the behavior of memory. I do lots of panoramic images--many more than 30 images. Well, PSCS3 now likes to say it is out of memory when working on these big'uns. In the past, when CS3 ran out of memory, it would just stop the processing and show PS open with no files loaded. This was fixed when I gave it tons (200GB) worth of scratch disk space. Now, even with 200GB of scratch disk space, I am getting out of memory errors on any panoramic over 25 or 30 images. I also have gotten the out of memory error after a few hours of work on large images. I just have to exit and restart PS to get it corrected, but it seems they might have created a new bug with the repair of the old bugs.
My system: AMD Opteron dual core at 2.4GHz with 3GB of RAM and /3GB switch turned on. WinXP-SP2. Nvidia GeForce 8600GS video card with 256 MB of memory.