as to how long it lasts, it'll probably work for a decade or more, but the mobo would fail before that, neither of which is the real question of how long it'll be useful for, i'd say they'd both be useful for your time period, becoming less useful near the end, though near the end of that period the base offerings from both would be faster than the i5 is now. BUT no-one really knows. There might be something really useful or interesting that you want to use them for in 2 years time that just happens to consume loads of cpu power, or there might not be.