In general, storage capacity depends on which image size and quality you have selected.
For your information, here is the number of images recordable in a 8MB SD Memory Card in the respective image size and quality. Since the image size may vary depending on scenes and subjects, these are approximate values only.
Economy: 13/25/39/117
Standard: 6/13/20/68
Fine: 3/6/10/39
Super Fine: 0/1/1/7
(Pixel Size: 2272x1704/1600x1200/1280x960/640x480)
Movie: 19 sec.
Audio Recording: 13 min. 43 sec.