The 4870 with its better memory GDDR 5 is a very good card the temp problems taht have been its nemesis have been rectified with the latest drivers, though an aftermarket cooler is a good idea. It is always best to read up on lots of reviews as that gives you plenty of info to make the right choice for yourself.
http://www.legitreviews.com/article/768/4/
http://www.techwarelabs.com/reviews/.../index_8.shtml
As to the cpu I have no experience of Intels but are not the Q6600's the best value at the moment ?
http://www.overclockersclub.com/revi...l_e8400/11.htm
http://www.overclockersclub.com/revi...l_e8400/16.htm