I made a very similar system except I used the 8400 with 1066 G.SKILL memory instead ... I recommend you do the same IF you plan to O.C. because the difference between 8400/8500 is minuscule if you turn it up to the 3.4-3.8 GHz range. Also the 1066 G.SKILL ram gives more headroom to turn up your CPU's FSB (can't go past 3.6 GHz with DDR2 800 RAM...which is sort of average on the 8400). I think this is even more significant if you are running a radeon 4870, with the possibility of going crossfire in the future...you will need a serious system to lean on those GPU configurations. Overall though your build looks great and my experience is limited so take my advice as a second or third opinion.
Agree with the Corsair change and the E8400 change - you aren't going to notice the difference.
You haven't specified a usage or time frame for this machine. If you aren't gaming much and want a long lifetime you could look at a quad core, Q6600 or Q9300. As programmers start sorting out multi threading the quads will come into their own over a dual core.
Not that I'm giving you more options and making things difficult!
You are about to answer a thread that has been inactive for more than 6 months. If you still wish to proceed, please ensure that your posting is original and does not duplicate or overlap any prior responses to this thread.