The standard Sandisk card is just like most other brands in that it is 2mb per sec. or about 10X. I have a Toshiba that is similar. I also have a Sandisk Ultra which runs at 10mb per sec. or about 60X. I found the best price for both at bannanapc.com. I had good service from them
One reason that you would need a faster card is for shooting in burst mode. It gives much better performance for high speed shooting. Both of my cards are 512 mb.
Hope this helps