Yay. Windows 2003 Server is finally installing on the SATA drive. After finding out that it indeed was a problem with the drive and the motherboard, a more guided search revealed an article on the Western Digital homepage that described how to fix the problem. The VIA VT8237 doesn’t support autospeed negotiation, so the drive had to be fixed at 150 MB/s by changing a jumper.
Now I’m finally where I wanted to be on Saturday already, and I can begin to install everything and move data between the two computers. I’ll keep you posted.