No, thanks, I'll restart it later.
"Are you sure? You really should restart your computer now."
No, I'm downloading some other upgrades.
"You really should restart now you know."
No, thanks, I'll do it later after I'm done downloading.
"How about now?"
Fuck off, I'll do it when I'm ready you twat.
"You've made some updates, and you need to restart your computer for them to take effect. Do you want to restart your computer now?"