The e7300 is 2.8GHz and the Q8300 is 2.5Ghz. speed isn't always a factor. If the app is multi threaded and takes advantage of 4 cores, the Q8300 will have a big advantage. If the app is not, the speed of the e7300 will have a slight advantage. The e7300 also has 3MB of L2 cache, and the Q8300 has 4MB which might have a light impact.
I'm not sure what you are asking about with the i7 comment.
Do you mean a 5870 will not bottleneck any current CPU or do you mean no current CPU will bottleneck a 5870. Video cards perform the output to the monitor, and does not feed the CPU (at least without software). Therefore a video card is not going to bottleneck a CPU. However, a CPU will bottleneck a video card. The faster the CPU can process the data the quicker it can get to the video card creating less of a bottleneck. The whole bottleneck argument it completely overused because EVERYTHING is bottlenecked in a PC by something else, it just depends on how large those bottlenecks are.
That's false,please read some reviews,old CPUs like P4's bottleneck a card like HD 5870 in some games,also please read what other say and then reply.
Since you have gotten your answer, i will close this thread before anything worse happens