I am looking to get my wife a digital camera for her birthday. It will be replacing a film camera for her so she'd be using it for digital prints, etc. I have about 2 weeks to work with here. I was looking at the SD400 and SD500 since they both seem to be nice small compact cameras which my wife would appreciate. Can anyone give me any advice here? Are the differences between the two enough to spend the extra $75-100 for the SD500? Does the 5 vs 7 megapixel make that much of a difference for digital prints (or any for that matter)? Also, any pointers where to buy would be appreciated. I was looking at BuyDig.com which seems to be among the cheapest online places without getting into the USAPhotoNation types. Thanks.