Now. Anyone who says they didn't just have a little soul-scream of rage at the sight of that window is a lying liar that lies. Lifehacker.com posted a tip a little while ago on how to thwart this window, and I thought I would be remiss in my duties as a friend - nay, a human being - if I did not pass it on. And, because I'm just that nice, I made an illustrated tutorial to go with it.
There are two ways to do this; anyone who's not afraid of the Command Prompt window need only go to Start > Run > type 'cmd' > OK, and enter sc stop wuauserv. You'll still get Automatic Updates - you'll just have to remember to restart on your own, at some point, in order for them to be installed.
If the very idea of the Command Prompt window makes you wet your pants, and/or, like me, it inexplicably is NOT LETTING YOU TYPE ANYTHING WTF, you can accomplish the same thing (with more options) like so:
Start > Run > type 'gpedit.msc' > OK > Local Computer Policy > Computer Configuration > Administrative Templates > Windows Components > Windows Update > Re-prompt for restart with scheduled installations. Tinker with the options there (you can choose to disable repeated prompts entirely, or enter an interval of longer than EVERY 10 GODDAMN MINUTES at which to be reminded, with an upper limit of 24 hours), hit 'Apply', and you're done.
A bit confusing?
( See it in screencaps. )
Ta-da!