Hi,
For the RAM size it is easy : 1 image in your case is around 4 Mo. I guess you can do you application with around 10 image (including 1 for display), which means 40 Mo. Plus say 20 Mo for the appplication and data and you are around 60 Mo.
To optimize the CPU speed :
1 - if you use a USB, or regular firewire, it will take around 60 to 70 % of CPU load to acquire and display at 30 FPS for a 2 MHz CPU with integrated VideoCard.
2 - If you use the NI firewire card or Cameralink card, they do DMA access and you get your picture 30 fps 1.3 Mpix for less than 10%, depending on the videocard.
So in you case, if you want to save the images and video, I would go with a NI firewire card (maybe IEEE1394b), and chose a high speed Hard drive.
Cheers