This will be my first build in the last 10+ years. (I've been lazy and bought systems, I will be getting back to my roots and building it myself partly to save money, party just because). The purpose of the system is a mix of writing and running engineering simulations, playing games, photo editing (in that order). I plan to run Vista Ultimate 64-bit. I will overclock, but not anything radical.
Thanks for the advice so far. I will switch to the Q9550.
As for memories, I was under the impression that it might be problematic to run 4 memory modules together unless I reduce the speed (hence the higher rated memories). Still, it may be worth the risk to go with cheaper memory. Have any of you gotten 4 x 2GB DDR2 800 to run at least at 800?