Your camera is a good one! As Tom said, use the finest resolution your camera will produce. Set the sensitivity to 100-200 Then, brace the camera.
The most unsharp pixes can bve traced to somebody pressing the shutter button like they were killing a very ugly bug!
Put your camera on the Auto program default, and it will probably do just fine.
Now: IIRC, Canons use AA bateries: take plenty of extras, but DON'T carry them loose in you pocket with keys or change. Short them, and they become really unhappy, and may even redefine your idea of what the term "hot rocks" means!
As far as memory: My buddy brags he shoots 1500 pixes a day at the race track. That's a pita to view, sort and edit! Your 8 gig card should be enough, but just in case something gets farbled, take another. That's the beauty of digital. They don't need much to keep them going. I used a 2 gig card in my Nikon, and it did fine for a week cruise, and I needed only two 2 gig cards for 2 1/2 weeks in Hawaii. I put my spare 1 gig card in my wife's Canon Powershot and it did her fine.
Have fun. Let your camera do most of the worrying for you!