I downloaded Ubuntu 12.10 - bit .iso onto a bootable USB and want to put it on to my 32 bit 12.10 system as a dual boot, using a totally separate 1 Tb disk [which already has data on it].

However, when I go to restart and hit F8 fir BIOS set-up, I can change all the settings except the boot search order. Is there some other way to force the startup to read the USB first? Is the fact that I cannot change the search order to do with the fact that the 32 bit OS was 'Installed in legacy mode' not 'EFI?

How can I rectify this? (This might be related -- might I need to update my BIOS for my Intel DX38BT motherboard? I think their last upgrade was 2009.)