Memory cards don't deteriorate after being used (properly). They can however get damaged from improper handling (ie getting wet, sticky fingers etc). If you want to try the Staples memory I would reccomend doing so BEFORE your trip. Buy it and take a few pictures and download them just to make sure everything is working alright. If you have any problems with the card you can return it with no hassles (Staples is pretty good that way.) Now, as far as how many pictures you can fit on a card, this depend on the MegaPixel rating of your camera. Just as an example, I have a 4 MP camera and a 1Gig CF card. I took about 800 pictures at fairly high quality (though not the best). These pictures look great printed. On our 3MP camera with a 512MB card, we can take about 500 pictures. Personally I prefer the larger cards. That way you're not carrying around a bunch of smaller cards. Kind of the equivalent of changing rolls of film! Also, as i said earlier, the primary reason that memory cards stop working is from improper handling which is minimized if you have one card kept in your camera at all times. Hope this helps, have lots of fun and take LOTS of pictures. Remember you don't have to print all the picturs but they're nice to have!