I ran a simple program in arduino that pulses...
1000
0100
0010
0001
Well you're wrong with that sequence, look at the link below:
http://www.google.fr/imgres?imgurl=http://www.8051projects.net/stepper-motor-interfacing/stepper-coils.jpg&imgrefurl=http://www.8051projects.net/stepper-motor-interfacing/introduction.php&usg=__MhQYun-Tg-EqsPLhKko5PLE6P1E=&h=279&w=289&sz=26&hl=fr&start=9&zoom=1&um=1&itbs=1&tbnid=6FhvXUU8gS1CFM:&tbnh=111&tbnw=115&prev=/images%3Fq%3Dstepper%2Bmotor%2Bunipolar%26um%3D1%26hl%3Dfr%26newwindow%3D1%26client%3Dfirefox-a%26rls%3Dorg.mozilla:fr:official%26tbs%3Disch:1&ei=-rdPTeuyAYX2sgaM4_yeDw