VirtualBox does not like to assign more than 1/2 of your total memory or processor resources to the client over the host OS. You can run into problems with supporting your hypervisor software. On the other hand, Windows XP was sold on machines with 256M RAM, and I had a '95 dual core machine with Windows XP Media Center Edition on which the motherboard maxed out at 2G RAM. You can't tell me ANY XP software can't run in less than 2G RAM, unless it specifically states the requirement before installation. Windows XP Home never supported 32-bit PAE or 64-bit processors, either. Newer Windows XP software would support multi-processors, but older software didn't even support that extension.
You would probably be better off by getting an nVidia or ATI graphics card which is supported under Linux proprietary drivers, loading the Guest Additions in the Windows Guest and enabling 3D acceleration for the guest.
LMDE Mate 64-bit, LM16 Mate 64-bit
Debian Xfce 64-bit, Xubuntu 13.10 64-bit, Xubuntu Trusty Tahr 64-bit, Antergos Xfce 64-bit, PCLinuxOS LXDE 64-bit