i always look at the hardware details...many prebuilt pc's have hardware that doesnt even have any kind of namebrand on it, just says made in taiwan.
acer itself doesnt mean much..just like hp or dell they bid out for parts and usually contract to whoever sells them the cheapest in bulk.
that doesnt mean it wont last for years and years, depends on alot so rather than gamble i usually just build one myself using popular namebrands.
even cheap namebrands can have better quality control than a part from a sweatshop in the middle of nowhere thats a division of some company owned by a guy named kung pow chi for example
also someone that gives it a positive opinion might have a different model than the one your purchasing meaning different parts from different places and you might not get the same positive experience...overall get the extended warrantee..its usually worth it.