How hard is it to put in a sound card? And is there a one that fits all?

I am buying a reconditioned computer and it has no sound card. I would like to have sound. But I know nothing about buying one or putting it in. Any help would be appreciated.

How hard is it to put in a sound card? And is there a one that fits all?
Simple .. Open the side of the case pop the sound card in one of the PCI slots (White slots about 10-15CM long) all PCI cards will fit all PCI slots , if its a desktop case make sure to get a half height card.
Reply:Yea, Just turn off power and open the case and put in the PCI Sound Card! Then when done.. Boot up and install the driver if needed! If using win98SE or XP the basic driver should be part of the OS! from scale 1-10 this is a 1! My mother could do it!