Ya the quad core isnt the way to go. If you want to spend a helluva a lot of money get a core 2 duo extreme 6800.
On aftermarket cooling: Zalman cnps9500, tt typhoon, tuniq tower.
Those are a couple good ones.
Newegg has a lot of cases, I would get a full tower if I were you. cm stacker or something.
For a mouse, wireless: g7 by logitech, wired G5 or if you like the feel of intelli mice microsoft Habu.
Keyboard: logitech G15
Speakers: z-5500
monitor: 22in. widescreen.