You can have my desktop machine when you pry it from my cold, dead .. wait, that one's already taken. In all honesty (and when I don't say that I'm lying) I think I'll want a desktop machine for some time to come. This is mainly because I like building, re-building, modifying, and adding to them, and so on.
You may be surprised to hear that I'm like that, too. For as much as I like laptops, I sure don't want to get rid of my desktops. I like the upgradeability and I like knowing that I can almost surely repair it myself if anything goes wrong.
I wouldn't call messing with computers my hobby, but I do enjoy it and it seems every few months I get the urge to upgrade something. I've built three computers from the case up and have upgraded just about everything in every desktop I've ever had. I'm currently in a period of calm and don't feel like upgrading anything, though I may have to replace the CD/DVD drive in my older desktop but I currently can't afford it. Besides, I recently had to deal with a nasty hardware problem in my newer desktop that turned out to be a video card that had gone bad. Troubleshooting that thing was very time consuming and it drained me of any desire to get my hands inside the box--for a few months, anyway.