If I have a PC running Windows XP SP3 32 bit on which VirtualBox is installed, could I install Windows Server 2012 in VirtualBox as it requires 64 bit?
From the virtualbox website:
VirtualBox supports 64-bit guest operating systems, even on 32-bit host operating systems, provided that the following conditions are met:
So for virtual box you need a 64 bit CPU (just about every x86 CPU from the last decade is 64 bits) and one with virtualization support (That is rarer. Usually that means a core i7 or an AMD CPU)
Alternatively you could try qemu and have it emulate 64 bits, but it would be extremely slow.
The other way around ( Server 2012 as OS and XP in a VM ) would work fine.