HTPC stands for Home Theater PC. Same thing.
Anyways, tell your mom wireless speakers are not the way to go. If she is concerned about wiring clutter, just have somebody professionally install the wires into the walls or something. Having an HTPC is fine and the blu-ray player is fine (although I don't know how it has to be setup) but I still say that your mom will be WAY more satisfied with a nice pair of floorstanding speakers, a sub, and good receiver to power them. Have her go to a nice home theater store that specializes in audio (i.e. NOT best buy) and have her listen to a good pair of floor standing speakers and I promise you she will like them way more than some silly 7.1 system.