Tech Quest

[Tellos Athenaios]

The bootloader should offer you the possibility to choose. The default option (usually the latest installed OS) gets chosen automatically after X secs, but you can press the up/down keys to manually select the one you want (and prevent the timer from reaching 0).

Just press enter when you've selected the one you want (usually the options to choose from is 2 times the amount of OSes on your system), and the system will load that OS in the selected modus as if you didn't have a multiboot system.

EDIT: Also: AMD64 proccessor typically are capable of emulating 32bit mode (which is how you can run a 32bit OS on it in the first place , so it shouldn't be too bad with drivers & stuff).