I had a one year old HP laptop die on me due to an engineering problem with the heat sinks. That's why I ended up get my iMac last June.
Though my parents last two desktops have been HPs and they've lasted.
Hit or miss I suppose.
Comparing a laptop to a desktop is like comparing a RV to a home. A laptop is much more likely to have problems because it is constantly being moved, hit turned upside down, carried on it's side, bad ventilation and more.
I know people who had their mbp's die after 3 years and they treated them like babies, however the clam shell design caused problem (common).
I would highly suggest the HP as it would be more cost effective, however I agree with other posters in showing them an iPad or iPod and see if it gauges there interest at all and then that might help weigh the decision.