Re: How do they stack up?
Well, I have an old IBM (before Lenovo) laptop and a new HP, I've also used a lot of Dell laptops, as for Sony I've never even touched one.
IBM (probably Lenovo too): Good build quality, sturdy construction and hinges, durable construction. Mine's 8 years old or so and still going fine. Since it's a business laptop, don't expect to find the latest graphics or a multimedia oriented display though.
HP: Good build quality, good hinges, good price. HP laptops are great for the average home user because you can get better graphics for games and they have tons of multimedia features not found in business PC's.
Dell: Fair build quality, reasonably poor hinges (at least on ones I've used), good battery life (at least on lower powered models), can substitute for explosive weapons if necessary. The Latitude D602 (I think that's it) laptops that our school has don't have much in terms of features, but they last forever on a battery and are probably relatively cheap if all you need is basic tasks. The same laptops are also known to have shipped with defective batteries that explode, but a recall was issued to fix this. The main issue is the hinges, they wear out fairly quickly and then the screen doesn't stay in place very well. My dad has the same laptop for work, and it too has weak hinges. As for higher end Dell laptops, you can probably get some good gaming features and such.