Your camera is manufactured to use a particular kind of expandable storage. You typically cannot change the type of storage that your camera uses. The popular types of storage card are:

• Compact Flash - one of the most popular card formats for use in digital cameras. These cards come in many sizes (from 32MB up to 4 GB) as well as different speeds. See below for more information.
• Secure Digital - designed for use in many digital devices including digital cameras, MP3 players, PDAs, cellular phones and camcorders.
• Memory Stick - works in an array of different applications, including your Sony MP3 audio recorder, video cameras, and computers with a Memory Stick slot. Capacity ranges: 32, 64 and 128 MB and Memory Stick Pro ranges: 256, 512 MB & 1 GB
• MultiMedia Cards - designed to interface with an array of digital devices designed to support the MultiMedia and SD card format – including PDAs, cellular phones, digital video recorders, and digital cameras.
• SmartMedia - works in various devices, including your MP3 audio recorder.
• xD-Picture Card - for use in Olympus digital cameras

Compact Flash cards come in many different storage capacities. The most confusing thing about Compact Flash cards is the speed rating. Faster cards allow your camera to write photos to your card faster, therefore allowing you to take more pictures at critical times. Each manufacturer rates the speed differently. Lexar media rates their cards with a simple X factor. 1X is equivalent to a write speed of 150 KB per second. The speed of their cards range from 4X all the way up to 80X speeds (the fastest allows you to write 12 MB per second).

SanDisk manufactures cards at 2 different speeds. Their faster card "the Extreme" is rated at a minimum speed of 60 to 66X [there was no information on the company web site about how fast their standard card is.

Kingston Digital Media also provides for 2 different speeds, the information on their website was very difficult to find. The Standard CF card is roughly equivalent to 10X and their 'Elite Pro' card is rated at roughly 35X.

The most simple thing to remember when buying a Compact Flash card is -- the expensive one (from a particular brand) is the fast one. If you are opting for budget minded purchases, you will definitely notice a write issue when taking lots of pictures in a short period of time. Faster cards mean more pictures in a shorter period of time [you'll need to decide if the 1 or 2 times a year that this becomes an issue for you is worth the increase in price for the faster cards].