atomでamd64版を走らせるにはEM64Tが必要だよ。

cpu0: Intel Pentium Pro, II or III (686-class), 1596.18 MHz, id 0x106c2
cpu0: features 0xbfe9fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR>
cpu0: features 0xbfe9fbff<PGE,MCA,CMOV,PAT,CFLUSH,DS,ACPI,MMX>
cpu0: features 0xbfe9fbff<FXSR,SSE,SSE2,SS,HTT,TM,SBF>
cpu0: features2 0x40e31d<SSE3,DTES64,MONITOR,DS-CPL,TM2,SSSE3,CX16,xTPR,PDCM>
cpu0: features3 0x20100800<SYSCALL/SYSRET,XD,EM64T>
cpu0: "Intel(R) Atom(TM) CPU 330 @ 1.60GHz"
cpu0: I-cache 32KB 64B/line 8-way
cpu0: Initial APIC ID 1
cpu0: Cluster/Package ID 0
cpu0: Core ID 0
cpu0: SMT ID 1
cpu0: family 06 model 0c extfamily 00 extmodel 01