deavod is correct! HA.. I just booted into my portege 3505 from my Lite On dx-20a3h-05. It sounds goofy but I tried for about a half-hour before reading this post. It simply would ignore the external cd/dvd drive. Then ,this is exactly what i did: I plugged the external drive into my Imac them when it spinned up I quickly unplugged it, turned on the portege then quickly plugged it into the usb of the portege-- all within a second or two. BTW, the bios is set to boot from cd. It actually worked and booted into the xp install disk!!
Lite-On DX-20A3H-05