their right, building a comp is not hard.
The hardest part would be installing the motherboard. All those mounts to put in, fiddly. Need to watch out for some cases though, was building a friend's comp a while back, and to get the cd drives in, the front panel had to be removed. Took 3 hours to get it off. Was help back by 10 pop-screw things. Was also afraid that if i just ripped it off, i would have broken it. Had that kinda feel.
Anyway, as someone else said, if it fit's in that slot, then it's probably meant to go there.