Sounds like this is a nice point and shoot camera but has little to offer in terms of manual controls. Do you want to take snapshots (parties, etc.) or do you want to do "photography?" In my mind, if your goal it simply to capture relatively high quality snapshots, the SD 700 would probably do the job well. If you really want to learn about photography as a form of artisitic expression, you will soon yearn for some sort of manual control over the exposure.
Aperture priority and shutter priority help you set the type of exposure or how the light gets into the camera. For example a wide aperture and fast shutter speed is good for capturing action without blur. A narrow aperture and slow shutter speed is good for capturing a large landscape clearly.
Basically, if you had any interest in the above paragraph, you might want to look into something like the Canon S3 IS or even an inexpensive SLR which will allow you to grow into it more. If you would rather not worry about all that exposure stuff and let the camera figure it out, go with the SD.