You could get a good laptop for that money, plug it in to your screen if you wish, and you have something much more flexible.
Personally I wouldn't consider a desktop these days as they take up so much room. With a laptop when it's not in use just pack it away. Also with the increasing use of smart phones and tablets to acces email and web even firing up a laptop seems a chore.
I agree to a certain extent. The main thing I dislike about laptops is if they break, they do not tend to be easy to fix for the average person. A desktop PC, more so a self build is much easier to test/repair due it's modular design and also upgrade if required. They also offer much greater internal storage if required. I had a Fujitsu Siemens laptop several years ago and it was a total piece of shoot. If I was buying another I think I would research the best brand and also the longest warranty.
I have an Android tablet and it is great how fast it boots up, but it still cannot replace quite a lot of tasks that a destop PC/laptop can do. I have a HTPC, but can also use it for other tasks, it sits underneath the tv and looks like any other AV equipment and can still be used for other tasks. So it takes up no room, but I know what you mean about a normal desktop PC if space is an issue.
