Desktop + Laptop, or just Laptop?
lsc: if you work for long hours on a laptop without an external monitor and keyboard, you are asking for ergonomic trouble.But buying an external keyboard and monitor, and making sure both are an appropriate height solves that problem.To answer your question, I personally prefer a separate desktop system.  It's marginally faster to set up, and more importantly, it means that I've got a backup when my laptop is out of commission.