Desktops ain't going anywhere. I just bought a new PC. Its a desktop. A laptop does not have the bang/$ as a desktop. It will be a long time if ever a laptop can match the bang/$ as a desktop.
Furthermore, desktops/HTPC(Home Theater PCs)/Media Centers will be moving out of the office into the living room. Our new system is recording TVs shows and I then burn them to DVD. I used to have loads of stereo components. Well I still do but they are boxed up sitting in the closet. A PC can record video, show video, burn DVDs, play DVDs etc. We only have a stereo and a DVD player hooked up to the TV at this point. Recording video takes disk space and that is not going to happen on a laptop. And to record the system has to be on.
Given that music is going digital and away from physical media the desktop in the living room makes far more sense than a stereo.
Later,
Dan