Memory Cards
Looking at the list of memory cards (on your web-site) I find the same brand and capacity such as 4GB SDHC are not the same price. How do I know which memory card to buy for a Nikon D5000?
Is there a difference in the quality of pictures?
there is a difference, a big one. first off, you need to make sure the device you are going to use with the memory card supports sdHC. I believe your nikon 5000 does. For a camcorder or a dslr camera you would bennefit from using a sdHC class 4-6. Class 4-6 have just started popping up causing the normal sd class 1-2 to fall. I think it is called sdhc extreme 3.