Thank you, but that's not my problem actually.
The problem is
to install the system. The installers don't recognize GPT.
BTW, maybe OT: Is it possible to somehow substitute the BIOS with an UEFI thing? Maybe through patching it?
So that the "chip" on the mainboard keeps his old name "BIOS", but it's EFI in it?
Sorry if that's a dumb question.
Edit2: Just found it, it is called coreboot, I will investigate in that. But go back to installing on GPT ;-)