Well, it turns out my motherboard wasn't defective: all Asus P5GD1 motherboards are defective in the same way, and my replacement failed in the same way. Luckily I found a solution and reinstalled Windows. However, I was unable to install Linux. Research suggests it will only be possible if I replace my hard drives with a Serial ATA drive (or buy a different motherboard).
Linux is looking a lot better than it did six years ago when I gave up on using it. I tried a Kubuntu live CD, and was very impressed. It automatically detected my video card and ethernet port, and gave me a friendly introduction to today's Linux. Unfortunately, I can't install it because it can't see the hard drives.
Broadcast flag update
Anyway, the record industry is pushing their greedy agenda again with their latest bill. Ars Technica reports (via EFF) that there's a new bill to force hardware makers to put draconian hardware restrictions in their digital radio receivers. It's not clear to me on first read what exactly the implications are of this bill--I should edit this post later when I figure it out.