what the 80x, 100x on the memory cards stands for?

The benchmark of 1X is a transfer rate of 150 KB per second.

I have not encountered a card that was not at least 4X (600 KB per second) and 12X (1.8 MB per second) is now a common speed for an unlabeled card. Compared to 4X, 12X might still be called "high speed" by some manufacturers. 40X is also a common "high speed" card and the transfer rate would be 6 MB per second. That's not too bad for most applications.

Sandisk Ultra II claims a minimum write speed of 60X or 9 MB per second, and a minimum read speed of 66X or 10 MB per second. Sandisk Extreme III claims a minimum write and read speed of 133X or 20 MB per second.

Once the memory buffer is full, you can not save images any faster than the card can save them and the camera will stop taking pictures until there is space available in the memory buffer. This means you are limited by both the size of the memory buffer and the write speed of the card. This is generally only a problem if you are shooting video or a series of continuous pictures.

See also: http://www.lexar.com/dp/workflow/Pro_HS.html

Sandisk and Lexar are the best known memory cards for digital cameras. I am sure that the cards all pretty much perform the same, but these brands have a lifetime warranty for some of their products, so that makes me think they are built to higher standards. As far as day-to-day use, I have some generic and some of each brand I named and they all work. The contacts on the brand name cameras seem to have the equivalent of the "thunk" that you look for when you shut a car door to check it's quality, if you know what I mean. You don't wonder, "Is it in there right?" because it just feels right. I don't buy generics any more, though. I just end up getting them "with things" somehow.

Mrs. Wright - 4th grade. She made a big deal of me writing little rhymes. She is probably the second biggest reason I write today. Mrs. Box - 7th grade English. She got me in big trouble when she called my mother to the school. She told mother I had a million dollar brain, and mama got proud, the she said that I used it like a $1.98 bargain basement special, and it was hard to sit for a couple of days. Mrs. Southerland - 8th rade English. She was a total riot and threw chalkboard erasers at students. Very memorable woman. Mrs. Smith - Art teacher. Had a major crush on her for years, even after graduating. Miss Rapp - 9th grade English. Her dress fell down once when she reached for something on the top shelf and the thin strap came loose. A memorable occassion, as it was her first year as a teacher, and she was gorgeous, even without a dress. Mrs. Conner - Bookkeeping and typing. Really sweet lady And one girl who was not a teacher, but taught me a valuable lesson. When playing chess against a gorgeous redhead, concentrate on the game, not the player or you will get beat in 3 moves, and that is not cool in the final game of the tournement.

these are high speed cards

the numbers tell you how fast they process the photo

any brand will do