To hold more photos at higher resolution you can buy additional 1GB or 2GB SD (Secure Digital) cards.
For use in SD compliant devices including : Digital cameras, Digital Photo Frames, Camcorders, Mobile phones, MP3 players, Navigation Systems, PDAs and Notebooks.
The storage capacity of a memory card you choose will depend on how many digital photos you want it to hold. Memory cards come in different storage capacities, ranging from 32MB all the way up to 2.0GB. How many digital photos that card can store depends on the resolution (megapixels) of your camera (picture). The higher the resolution or megapixels, the larger the file size and the more memory each photo uses.
Here's a quick guide that can help you decide what capacity of memory card to buy: A 1GB Card can hold 409 images from a 5 megapixel camera and 320 from a 6 megapixel camera. A 2GB Card can hold 818 images from a 5 megapixel camera and 640 from a 6 megapixel camera.