I have here a little bit uncommon system: its primary hard disk can't have an old, DOS (MBR) partition table, only a GPT type. It is an outer restriction, that nothing can be done about. It seems as if the firmware silently rejected the disk writes to a DOS (MBR) partition table.
I am thinking about a Windows Server 2008 install into that system. Is it somehow possible?
When you say "EFI-only partition table" I suspect you're talking about a GUID Partition Table (GPT). Per Microsoft, Windows 7 and Windows Server 2008 can boot from a GPT, provided you're running an x64 build in a system with UEFI firmware.