I would like to know what is wrong with this code:

[BITS 32] ; Windows XP SP2 32-bit

section .text

global _main

_main:
push Command
mov eax, 0xAABBCCDD ; address of system()
call eax

Command:
db "echo whatever"

Note: This is shellcode, so it's going into a char[] in C. Therefore, the string at the very end doesn't need to be null-terminated.