For me it would be the after-care support that would be crucial. After having my fingers burnt more than once with crappy Acer support staff - "sorry Sir you've invalidated your warranty by taking off Vista and putting on XP".
Or the three MONTH warranty on their keyboards and mice (are they really that crap you can't guarantee them for a full 12 months?)
Or the laptop which was sent away for repair, fixed and then returned when we were closed. So returned back to Acer who couldn't find a fault and tried to charge us for it.
I'd rather buy second hand HP gear from Ebay thanks.