Digital Camera Memory Cards

Does it really make a difference what size memory card you use?  To your camera, no; to you, however, it could mean the difference between getting the picture you want or running out of space on your memory card.
When choosing the most logical size, take into account how many pictures you usually take at a time.  Your needs if you are a world traveler will be different from those of a person who only uses a camera for holiday get-togethers.  You also need to decide how big the files are of the pictures you take.  Smaller files such as pictures for online will take less space and enable you to fit more on a card.  Larger files for printing will need more room.
 If you have a 2 mega-pixel camera, 128MB is usually enough. For a 3 or 4-megapixel
camera, a 128MB or 256MB memory card is usually plenty. For a 5-megapixel camera, start with a 256MB memory card.

Here's a rough guideline of how many pictures a flash memory card can hold:
*A 128MB flash memory card can store about 21-41 large, uncompressed images or up to 100 small, compressed images.  This is good enough for most photographic needs.
*A 256MB card will store about twice that, 42-82 large pictures and nearly 200 smaller ones.  Important events like weddings and once in a lifetime events might warrant this size just to make sure you don’t miss that one special moment.
A 1GB card has room for nearly 4 times as much as a 256MB card, If you are planning a long vacation with a lot of picture taking, this might be best with the capacity to hold 168-328 large images and a total of close to 800 smaller images.
Whatever you decide, remember you can always use several smaller cards and just change them when they are full.  It only takes a few seconds to switch memory cards, so don’t panic if you don’t have a large memory card.