Thanks, seems you were right. I somehow managed to identify the right bag (only one with 10 screws) and then pick up a different one. The screws still seem a bit on the short side, but they seem to have taken alright when screwed in (Q-Shield also needed to be all the way in).
While I'm at it, there's a component on the mobo that's labeled "AMD SB950" in the motherboard's instructions booklet, and has "Asus the Ultimate Force" written on it, which has a plastic film over it. I don't see anywhere in the instructions where it says to remove this, and it doesn't quite look like it was meant to be removed, but I feel a bit uneasy about it. Should I remove it?