Some of my own statistics for broken PC's/laptops over the past 10 months where the motherboard died and needed replacement, but because it's out of warranty, the costs are too high to replace.
Medion Laptop: 1
Medion PC: 4
Packard Bell Laptop: 1
Packard Bell PC: 0
Acer Laptop: 2
Acer PC: 3
HP PC: 3 (2 of them were just out of warranty)
HP Laptop: 9 (7 of them were just out of warranty - most of them are from the DV9000-series)
With Dell, Packard Bell, Sony Vaio, Mac, Samsung, Asus systems I never encountered faulty motherboards yet in that way that it needs replacement.
I won't say HP is a bad brand, but the numbers don't lie. The complaints about HP laptops worldwide are huge and a lot of factory-errors are not even supported, even though HP admitted two years ago that there were a lot of problems with their motherboards, going in conflict with Nvidia-cards. Repaircost: 500 $ when out of warranty. Problem is that most of them got broken, just out of warranty. Customer = screwed.
At the other hand, thanks to HP, I've managed to build up a huge amount of spareparts such as Hard drives, Memory, displays, Wireless cards, etc
Nevertheless, HP systems with good working hardware are working just fine.