I've professionally worked with Compaq/HP, Dell, and now IBM (lenovo).
As far as durability and quality goes, I would say IBM has the others beat. But they lack a little design (which is up for taste I suppose) and usability. HP laptops for the business market are relatively nice, but very average in all respects. Dell laptops have a nice look, good service, good quality, and great displays. They also offer slightly better performance laptops than the others do for the same price.
As for most other brands, I am not so sure they work in a corporate environment with their service network and small customer centric approach. They sometimes offer slightly better value, but almost always less quality. Yet I must agree that Sony is working hard on becoming better than the rest.
(By the way, hi!)