Your cpu is probably so old it doesn't support nx (so won't show up in bios and doesn't support w8). If you know what cpu you have, it would be easy to look up. W8 needing nx slipped my mind. It also needs pae and sse2 but if it has nx then it'll have those too. My comment before still holds true, it doesn't matter about bios version, the hardware needs to be compatible. The upgrade adviser would catch the incompatibility.