id go for the 6800GT and a X-2.
since the "bottlenecking" 6800GT isnt cause trouble atm (because it runns everything on highest settings fine.) and the processor is a bit more furureprrof id say.
(but ah well.. its the same decission ive made )
id say 'carpe deim'. go with the 7800gtx or gt and x2 4400+ like i did. then revolve everthing else around that. just those 2 would be around $1000. that leaves u with +/- $600. u can definately get quality components with 600 unless u need to get an LCD too.