Today, my Vista PC prompted me to install Service Pack 2. How comes they don't know the update size?

I went for it and after some downlaod time the system started installing the Service Pack:

I was worried when it told me it was going to take "an hour or more". So I twittered an "Installing Vista Service Pack 2 and crossing my fingers" message, and went working on another computer, as recorded on the facebook thread.

In fact, after less than 5 minutes from this message, it finished, rebooted, took about 10 minutes for rebooting... and it was done. Much shorter than Microsoft had told (or threatened) me. Now I understand they want to warn people of the worst possible scenarios, but it would be like Google Maps saying it will take 5 hours rather than one, just in case of traffic. But I'm digressing.

So after those 15 minutes I got:

So, yes there was in fact a second restart. A standard one, and Vista told me I was OK:

Everything went fine (I started recording images in case of problems), but I'm not sure I gained much by giving up my PC for half an hour. As mentioned on Facebook, Vista still took its 5 minutes to determine that my gateway is indeed connected to the Internet, blocking any web access during that time. As it does every time. The problems seems it does not know about the router, which in fact is a special purpose Linux box!

Anyway, from my personal experience, this was a smooth update. Ready to migrate the computer to Windows 7, though.