As you have asked about warranty and reliability....
I am responsible for about 300 machines with the majority of them being HP, over the last two years I have had to make one single warranty clam with HP for a faulty hard drive on a laptop (and to be honest that was probably caused by the end user being a bit rough with it!). I reported the problem using the on-line warranty claim on their website at about 2pm one day and the replacement hard drive turned up in the post by 11am the next day. Can't beat that in my opinion.
Keep in mind that no warranty will cover you for problems with the software installed on the machine, warranties only cover hardware.