b&w 683 are very good speaker for 1.5K, if you can get it half price, it is a steal.
however, if you can get full line of B&W speakers at 50%, u should get a pair of 804s, which normally at 35K, but after 50% off, it only $700 more than 683, and i would say it would be the best $700 upgrade u can get.
i first listened to the new 600 lines, and they sounds pretty good. change to CM series, they sounds pretty much the same as 600 series. The CM7 sounds brighter than 683, but 683 has better bass extention. however, after listened to 800 series, those are in a totally different class comparing to 600 and CM series. the detail was incradible.
unless you want to play certain games only available on Xbox, why not just get an PS3 and u don't need to buy a dvd player nor a blue ray player. use the extra cash toward speakers. in addition, PS3 can do very good upconverting on DVD.