Nikon's website has a list of approved and supported memory cards, available here:
http://support.nikontech.com/cgi-bin/nikonusa.cfg/php/en duser/std_adp.php?p_faqid=5097&p_created=1056053247& amp;p_sid=CJk_o6_h&p_lva=&p_sp=cF9zcmNoPSZwX3Nvc nRfYnk9JnBfZ3JpZHNvcnQ9JnBfcm93X2NudD0yMiZwX3Byb2RzPTEsN DYmcF9jYXRzPTE3NiZwX3B2PTIuNDYmcF9jdj0xLjE3NiZwX3NlYXJja F90eXBlPWFuc3dlcnMuc2VhcmNoX25sJnBfcGFnZT0x&p_li=&am p;p_topview=1
The bigger the card, the more photos. Exactly how many photos will depend on the photo settings - size, quality, etc. Find out how much internal memory the camera has and check how many pictures it holds, then multiply accordingly - so, if you have 32MB internal memory and it holds 32 pictures, you know it's 1 picture per MB and a 512 card will give you 512 more pictures.