Lately I had cloned a physical XP installation to run it into VirtualBox.
It went fine except for the network drivers.
1-Download the proper driverpack (lan, wlan, storage, etc) for the correct O.S (nt5,nt6,x86,x64).
2-Unzip it to a folder (c:\drivers for exemple).
Note1 : I mounted my disk image offline to inject my files.
Note2 : for a physical machine, best would be to stuff it all on a USB key.
3-And run dpinst from the command line (dpinst /path c:\drivers) OR use my GUI (here) to make it easier.
And voila, all needed drivers will be installed 🙂