Theres two types of mobos, one of them is called discrete motherboards they don't have integrated graphics, but they have an agp slot or pci-express slot to install a graphics card into. Then theres integrated motherboards they have an integrated graphics but SOME are limited because they don't have an expansion slot for a new graphics cards, but some new ones and even old ones depending on what u define old do.
I don't know what you mean "at least for 5 years" any computer and hardware in it can last far longer than 10 years, the hard drive may die off a bit earlier, but the point is that all has to do with maintenance the user and a simple roll of the dice.
I recommend you don't open it up if you don't know whats going on though trust me some people are a bit of a pain in the a** if you aren't able to fix their pc even if it has to involve them paying up for parts or maybe you simply don't have the means too fix it. Just tell your friends mom to take it to a reliable source, i hear best buy is good but very overpriced. Then only reason i even recommend them is because my friends usually take their pcs to privately owned local shops and they end up telling them they need a new cpu when in fact all they needed was a simple 4 step Warez spyware removal guide, and or a reformat.
But w/e happens gl and be careful.