Memory card slots? As in slots for CF, SD, MMC, and other cards? Apple laptops don't include these, and I am glad actually. With changing memory standards, it is not likely a laptop with these slots will support everything after being a year old. The 15 and 17 inch models do have PCMCIA slots though, and card adaptors work fine in there. And all models have USB2, and work fine with the standard USB card readers. I have a very tiny one for my memory stick duo media that my camera takes, it just sits in a pocket in my laptop bag for the rare times it is used.

If you are asking where the memory DIMMs are, all powerbooks have memory access via a screwed down panel on the bottom of the case.

Regarding the 128 VRam, do you intend to have a second monitor attached frequently? If so, that dedicates half the ram to one screen and the other half to the second screen. Expose can get noticibly choppy with several windows open and only 32mb per display.

For now, that is about the only advantage if you have no plans on gaming on it. Core Image in Tiger seems to be used by Dashboard and such, so it is more eye candy pulling on the GPU. Likely though, 64mb will be plenty even for the dashboard effects on a single screen. Dual screen, and it could become choppy again.