• Adobe's Photoshop Forum is one of the most helpful forums around, not
a snake pit as was stated.
• I used a 15" 1.67 GHz G4 PB with PS for years with 1.5 GB RAM and PS ran reasonably, but that is pretty much a minimum box for PS. G4 PBs were the first PS-acceptable laptops, the best G3s were so slow as to be unusable. The G4 PBs are fine laptops, albeit aging; mine died so I bought a MBP.
• Aperture also ran on that box, but I did not throw a heavy Aperture load at it. If you do intend to attempt Aperture as well as PS I would fill out the RAM to 2 GB.
• OS 10.4.11 and PSCS3 are very stable, but OS 10.5.x has been very problematic with PS. Bad enough that Adobe stated that PSCS3 would not be compatible with OS 10.5.x until at least OS 10.5.3. Users on the
excellent Adobe Photoshop Forum at
http://www.adobeforums.com/webx/.ee6b362/ seem to find OS 10.5.3 much improved but not totally problem-free. Personally I am remaining on OS 10.4.11 for now but will likely upgrade to 10.5.3 soon to take advantage of my retrofitted HD2600 XT graphics card.
Good luck!
-Allen Wicks