I would go for the extra .4 ghz.
Instead of seeking out a specific computer, it is probably best to build your own computer if you want a 4GHz processor. Intel finally has a consistent line of processors that clock at 4GHz without power issues, so finding someone who can build the tower for you is probably a better option than seeking out a pre-made computer.
1:1
Definition: In FM technique, the frequency of the carrier signal changes according to the instantaneous amplitude of the modulating signal. Hence, the frequency of the modulating signal is of irrelevance here and the devition from "fc" will be dependent on the amplitude of the same. considering 2GHz and 4GHz to be digital signal the ratio would be 1:1.
100mph
it would be about 4Ghz
No answer is possible as the frequency shift is proportional to the amplitude of the signal at any time. The frequency of the the two input signals is irelevant.
500 Mhz to 4Ghz
would be about 4Ghz
Yes, laptops are very handy and very durable. At times, they can even be more reliable than a computer and are often much faster too. The laptops with 4ghz are very reliable.
Intel never quite reached 4GHz with the Pentium 4. ... With each subsequent generation Intel inched those clock speeds higher, but preferred to gain performance through efficiency
A system bus frequency is 1600 MHz. A CPU frequency is 166 MHz to almost 4GHz.
Pentium4 is superior. It can clock of up to 4ghz, whereas the atom may reach about 2ghz max. This makes sense since Atoms are only meant to be in netbooks and thus they require maximum battery life. This means that less voltage goes into the Atom.