I'd have to disagree on that one.
I service Dell systems for a living, and so while some of their designs are less than optimal (the Optiplex 2xx series comes to mind, and virtually every small form factor, let alone ultra small form factor) every time I've tried working on an HP/Compaq system, that makes even the worst Dell designs seem excellent.
I also service Apple systems, and while I'm a huge fan of the Mac Pro case, which is an absolutely beautiful design internally with everything being on easy to pull out trays and aside from the optical drive, completely cableless. The iMac G5 was also a pretty good design from the technician's standpoint. Set it down, undo about three captive screws, and just yank the back off. All their new designs are just awful. You don't even want to know what a pain it is to replace the motherboard in a MacBook. And the new aluminum iMacs require you to take off the glass cover, which is untempered glass, then you have to take out the display, before you can get to any of the other internals except for the RAM which is located at the bottom.
So, I'd have to say the tech they sent out to fix your system probably didn't really know what he was doing. To be honest, Dell's certification process is a joke. It's an open book, no time limit, online test. And a lot of the questions are very poorly worded, or they'll put in questions where the answer is nowhere to be found in the reading material.
But every now and then you do run into a problem that gives a lot of false readings. On a couple of occasions I've been called out to try and fix something that looks like one problem but turns out to be another.
And there is some actual evidence that HP systems have a higher failure rate. The company SquareTrade sells extended warranties on electronic devices. They recently did a survey of about 30,000 laptops and according to their figures Dell has an 18.3% failure rate within 3 years. HP ranked last with a 25.6% failure rate within 3 years. Incidentally, Acer had a 23.3% failure rate within 3 years. Which seems to be pretty much in line with my contention that HP and Acer are duking it out for the right to say they make the biggest pile of crap. Seems HP is winning at the moment, but Acer is nipping at their heels. Probably within the margin of error on the survey, so they could well be neck in neck. So basically, 1 in 4 HP laptops can be expected to fail within 3 years. Dell is a bit under 1 in 5.
http://www.squaretrade.com/htm/pdf/SquareTrade_laptop_reliability_1109.pdf For all the gory details.
I myself have an Inspiron 530 desktop that basically runs 24/7 except for about 2X a year when I go on a 1-2 week trip to visit family half way across the country. Served me well for about 1.5 years. I also have a Studio Slim that I've used as a HTPC for about the past 7-8 months, and has served me well. I have had a few minor issues with my Studio 17 laptop. First one I got was defective, but they replaced it. The replacement has been pretty reliable. Enough so that I plan on replacing my two desktop systems with a Studio XPS 8000 imminently. I'm perfectly willing to eat my own dog food so to speak.