I'm recommending ESET Smart Security 4 to my neighbor. He has four PCs and is considering a 4 user license for two years. One of this four computers is a 64-bit system. If he purchases the 4 license two year package, can he install three 32-bit systems and one 64-bit system or does ESET require the purchase of 1 three user 32-bit license and the purchase of 1 64-bit license? Regards to everyone. My ESET SS4 installed on an Intel i7 system running Win XP Pro x64 doesn't cause me any problems.