well i will never say yes to lynnfield as it dies on jan 9. you should have gone for sandy bridge. but the current scenario says that you should not wait more then december 20 for sandy bridge motherboard lists.
and since you are getting a second hand 760 iam not protesting much

though iam suspiciious that your friend will himself go for sandy bridge lol.
by the way guys can cx400 handle gts450 , ithink thats the best card op can go for , not sure though if hell be able to get 550 riding on that. do seasonic 400 and 430 make any sense here?
and for mobo go Msi p55 cd 53 or msi p55 gd65 awesome boards.
and your usage asks for a greater monitor than graphic card.so you can get a good psu and display and add a entry level card. 5450 is concidered htpc god though.