I can certainly see the logic in the above comments about buying/using a laptop solely for DJ'ing, and absolutely nothing else. EG: Not letting all those extra drivers, and registry entries detract the PC from doing its job.
However, that does mean that a £700(or more) laptop is then dedicated to the one task. Other DJ related tasks, such as invoicing my clients, keeping track of everything that my (rotten) Inland Revenue Self Assessment Tax Return is going to want to know about, SMS-mailshots to anyone who's text'd me requests at "so and so's" party two week ago etc, etc would have to be