Optimum Sytem Setup

Hi All,
This is my first post so please be gentle! I've been sat in the wings for a while, researching every aspect of flight simulation and cockpit building and am simply blown away by the helpfulness and enthusiasm of you all.

I have FSX which I've been running on my laptop with a Saitek Yoke and Quadrant. The laptop is just too slow so I've decided to buy a dedicated pc just to run fsx.

After much research I'm still not clear on what the optimum setup should be, dual or quad? Best graphics etc etc. Initially I thought I'd just buy the highest spec everything but have learnt that this doesnt necessarily do the job correctly.

I want to be able to run a ton of addons such as the Mega Airports etc and would really appreciate some guidance on exactly what system I should be buying.

Thanks in advance...!