Sir Humphrey Appleby, "Yes Minister".
Frankly, the new technologies that allow me to boot up my computer and resume my work where I left off in a matter of seconds make it much more likely that I will turn my computer off when I'm not using it.
I've never understood the machismo behind "345 days without rebooting". Unless you're a mission-critical server.
I pay the electric bill, so if I'm not using it, it gets switched off.
"Don't worry, your data is encrypted with 256-bit RSA."
"Computer experts have cracked the encryption."
So why doesn't the fantastic mathematically complex encyption ever work? Why should I trust https? Or any other encrypted transmission?
Then start Earth 2 on Gliese 581d.
It's the only way to be sure.
(We'd put all the telephone sanitizers on the 3rd ship, right?)
I usually find that a faster CPU equates to a computer that is useful for a longer period of time before becoming unable to cope with up-to-date apps and OSes.
You can buy more RAM at any point in the machine's life and install it yourself, but that isn't always possible with a CPU.
The golden rule is: don't get a machine that is "just good enough for now": buy some "future" too. Also, don't be an early adopter.