My computer has a x64 cpu. Because I have some old soft- and hardware for which no 64bits drivers are available (i.e. Canon scanners), I like to reinstall Windows XP x86 (32bits), together with the OS that I use most, which is Windows 7 x64. So, I want a dualboot pc with WinXP x86 and Win7 x64. Both OS's run on the same pc but never at the same time. I know that NOD32 AV 4.x is available in 32bit and 64bit versions, of course the 32bit version will run when XP is active and the 64bit version when Win7 is active. How many licenses are required in this situation?