Just about any SD card will work, but I would recommend getting a high speed card.  I had previously used a standard 2 GB card and it would take about 10 seconds to save the picture and data on a snapshot and would take more than several seconds for a recording to start.  It would take long enough that I would think the unit had crashed.  I replaced standard card with a 'class 10' 4 GB SD card.  Now snapshots save and recordings start almost  instantly.  I think I paid $12.00 on newegg.com for the card.