Hyper-V is useless crap
On Windows 8, no more XP-Mode - one of the things that made Win7 successful. Although Win8 comes with Hyper-V, it has two many troubles and limitations. If you're migrating from XP or Win7 with XP-Mode to Win8, this is the most painful part.
For example, Hyper-V does not support USB; thus I cannot install the driver for HP C4280 printer. The stupid HP driver refuses to install if it does not see any USB on the machine. I use printer servers for my old USB multiple function printers. I don't need to plug them into my computers and I can print and scan wirelessly.
I use Airlink101 multifunction printer servers for my HP and Canon USB printers. It lacks of 64-bit support but worked like a charm in XP-Mode on 64-bit Windows 7. I also loved the seamless integration of Start menu, almost never realize the XP apps are running in a virtual machine. Very convenient.
Now with Hyper-V, the Airlink101 driver, the (virtual) remote USB bus (BusRMUSB.sys), no longer work. I lost all my faith in this Hyper-V. If a driver that has always worked in XP, physically and virtually, but won't load in Hyper-V, something must be seriously wrong in this virtual engine.
Another stupid thing with Hyper-V: no NAT for internal network.
Even stupider: no any kind of share or integration between the host (Win8) and guest (XP), other than ordinary networking facilities through bridged network. For example, if you want to let XP access your USB drives, remote desktop is pretty much your only choice.
VirtualBox is still not in its primary time
So I went to VirtualBox. It had no above problems but it had its own. It does not take the advantage of Intel VT-X hardware acceleration for virtualization. It uses at least 5% CPU even during idle. These shortcomings are not acceptable for an Intel 2nd gen i5 laptop. Furthermore, its USB implementation is still a PIA.
VMWare is the pioneer and still the king of virtualizaion
The best thing about VMWare: you can make changes such as network type on the fly, no need to restart or shutdown the VM.
The bottom line: if you need "XP-Mode" in Windows 8, don't waste your time, go straight to VMWare Player.