Can't really comment on what AutoCAD needs - probably the most cpu-hungry piece of software you mention - but I would avoid laptops or similar compact machines if you are going to use them anywhere near your new machine. My first garage pc eventually started randomly shutting down in the middle of a job. Turned out to be the cpu heatsink full of dust causing overheating. Dust builds up everywhere inside. Laptops are much more sensitive to this and much more difficult to clean out. A decent-size desktop machine lets you take a panel off and stick a small vacuum cleaner nozzle inside. In a clean office environment, take your pick according to power needed/size/budget. Personally, I prefer to avoid laptops as you get more power/speed/reliability for the price from a desktop but if you need portability or small size, you have to compromise somewhere.