I already had a monitor and external DVD drive therefore it would be practical and cost effective to do. I noted that everything fitted nicely in the cupboard but also noted that the dvd drive wouldn't open fully, that's where the external drive came into use. With the cupboard door closed I also noticed some heat build up so I removed the shelf and cut two holes for some medium sized case fans. I also used double-sided tape to mount the external DVD and hard-drive out of the way.
I bought a cheap usb hub in order to run the extensions to my desk. I had to extend the 5.1 speaker system cables which was easy enough. It looks a bit messy for now but I'll neaten it up a bit more.
Before you purchase monitors and keyboards etc. make sure your laptop has an external monitor port.