Don't forget the X-Box.. they are brutally powerful (I got me one of them too!!).. and have vastly superior on-line and multimedia capabilities.. You can even download TV shows and movies on them now. The realism of the graphics are outstanding.. and if you like violent shooting/fighting games, there are some really good ones out there now..
But If you're looking for all round family fun, I agree the wii is the better choice.. its aimed squarely at the 'non gaming' market.. If you're an adolescent male with a thirst for blood and naked flesh however, the X-box is a must!! (personally I think any serious gamer will probably get both)