I don't think brand really matters. SANDisk has been around forever and I think they sell it at SAM'S Wholesale Clubs CHEAP.
Let's say you're going to take quite a few pictures each day for a week-long vacation before you ever get a chance to download them onto your computer. If you have a 3.1 Megapixel camera and you take the largest pictures your camera can take, they'll be around 500 KB each. So, with a 128 MB card, you could take around 250 pictures on one card before having to move them off the card and onto your computer. That would be around 35 pictures per day for a week.