.386
That cannot work, the 386 processor didn't have this instruction. You have to target .586 (Pentium and up) and explicitly state that you want to use the MMX instruction set. Fix:
.586
.mmx
That will get the assembler to accept the MOVD instruction. Next thing you'll have to do is fix the operands. Moving from ebx to eax is not valid, and pointless, you'll have to specify an MMx register.