Everything goes smoothly, and Windows boots. Then Windows says, and I'm paraphrasing here:
"Let's see if you have new hardware. Oooh! You have a new motherboard! And you've got a new NORTHBRIDGE! And a new SOUTHBRIDGE! And look at all these peripherals! SO MUCH NEW HARDWARE! TODAY IS THE BEST DAY EVER!"
And it sits there for literally five minutes installing drivers for every piece of hardware in your entire computer.
Which is irritating because, for some reason, it invariably gets to USB last, which means your fancy USB mouse and keyboard are totally useless for about five minutes, and if any errors pop up, sucks to be you, you can't get to them!
So I invariably end up sitting there for five minutes wondering if every silence means Something's Gone Wrong, and occasionally moving the mouse back and forth to see if it's woken up yet. Nothing ever actually has gone wrong yet. But I still worry.
Also, my computer has been through so many motherboards and ethernet cards that it's now up to Local Area Connection 14.