32MB is a teeny tiny capacity that will only allow approx. 7 Large/Superfine images, so you will need to buy a memory card with much more capacity.
Your User Guide has a chart in it (pages 203-204) that shows you approx. how large each image file is and how many you will be able to take per 2GB or 8GB, as well as the measly 32MB card that Canon so generously gave you. For the best image quality possible, make sure you only shoot in Large/Superfine. This means each image file is larger...but memory cards are cheap, so it shouldn't be an issue.
btw, there are approx. 1000MB in each 1GB...so you can see that 32MB is useless to you.
I recommend you buy a reasonably fast, 4GB SDHC Memory card as a minimum capacity. It will allow you to shoot approx. 1000 Large/Superfine images...or just over 30 minutes of the best quality video.
A Sandisk SDHC memory card is my recommendation. It's available in the Ultra II (Class 4 speed) at around US$10...or the faster (Class 6 speed) Extreme III for under US$20. Do NOT be tempted to get a cheap standard speed (Class 2) card, as it will be much too slow for your camera.
Make sure you always Format any brand new memory card before you use it the first time. This is done in the Camera's Menu. Your User Guide explains how to do it (page 156).