A laptop is better than a desktop if comparing 1 on 1. But for the the money you spend on a laptop, you can get a more powerful desktop for less money, then use the left over cash and just buy a cheap netbook for word processing and internet browsing on the go. Online file-sharing makes it easy to access any files you would need from either device.
My current laptop is on its way out so I'm gearing up for the desktop & netbook combo. Traditional laptops are not powerful enough to be a home computer (for me, at least) and are too big to carry around constantly.