Dell has a fantastic warranty, i always loved it.
One thing i will knock HP for is definitly the customization. You can customize them, but you have to call them and it is a little involved. Dell makes it very easy, and i always liked that. I havent looked for business, but i use mine for general, gaming, and development and it really fits the bill. And your right, it is VERY light and definitly a solid professional looking laptop.
If we could get the lightweight and general layout into a dell, as well as the pricing, they would take HP imo. Each laptop i have customized for friends/family has been cheaper through HP. My dads, for example since its the most recent, was 450.00 more through dell for the exact same thing, before warrenty stuff.
As far as HP for warrenty service, we have only had to make two claims. One laptop suddenly lost all the blue led lights for the quickplay buttons at the top. I called HP and they sent fedex out the next morning. Fedex packed it up with me and it was overnighted to HP. That was on a tuesday. On thursday fedex came back with my laptop, good as new.
The other incident was a DOA harddrive. I called them up and they overnighted me a replacement, i installed it and sent the other back. Dell did the same for me with desktops, but they always tried to argue with me about what was actually wrong. HP didnt ask any questions. Neither time did it cost me a dime.
Overall i am very pleased with both companies, and if we could get the pros from both in one pc, we'd really be jamming.