Both are good media players and have their pros and cons

HTPC are powerfull gadgets, (for power hungry ppl) well consider it an all-in-one, where you can surf the net, skype/msn/yahoo around, games, at the same time download RS/MU files etc but configuration comes quite costly indeed

Media players are mainly for simplicity (ease of use), portability and for the computer illiterate ppl (sorry) so mostly, elderly will find it very usefull to manipulate. just DL from PC/HTPC/Notebook dump it in and it works like magic.