New Motherboard

I am using a P5Q Deluxe and I have nothing but good things to say about it. If you want to overclock, it can be a little daunting. I stumbled across an excellent thread over at Xtremesystems that deals exclusively with this motherboard. Lots of good information and advice. The P5Q's should have no problem with either the Q9650 or the 4870X2 though I can't say that from personal experience. Though through following that thread over at Xtremesystems, there are a few users with the same or close to the same setups.

As for the RAM question it is almost always better to run 2 DIMMS versus 4 DIMMS. Running 4 DIMMS will result in the motherboard running your RAM at a Command Rate of 2T which will have a slight negative impact on memory performance. Also if you actually match your 4GB of RAM with a 64 bit OS, heaven forbid you actually come to the point of needing more RAM, you still have free DIMM slots to add memory.

One thing I have to add about your motherboard choice is that ASUS has been taking a lot of heat over very poor customer service / support. I can't speak to this personally because I have yet to have any problem with any motherboard from them. I have dealt with GigaByte's technical support and I have to say I was satisfied though I would have been happier not to have to deal with them at all.