Anything with at least 133x write speed would do nicely. I use PNY 266X and prefer it over Sandisk or Lexar. Had error problems with Sandisk on more than one occasion. The faster the better since the 6.5fps can really fill up the buffer at higher shutter speeds. The fast write time can actually let you squeeze in a couple of extra frames before it fills the buffer. I shoot RAW so the buffer is like 16 or 17 frames. I have been able to get 18-19 with the 266x over the Extreme III's 133x if that helps. Not mind-blowing, but sometimes those frames might catch what your after.