if your getting the GIGABYTE GA-P35-DS3R LGA 775 Intel P35 ATX Intel Motherboard .. then yeh. flip out pop in.. simple as that
just to let you know that mobo is not sli thou.. you also will need some ArticSilver 5 thermal paste. Theres loads of tutorials on how to apply thermal paste correctly, just google it. You dont need to install anything it should work out the box... but usually best idea is to clean install operating system with new hardware.
just to clarify... you want the Q6600 G0 (basically its second revision, less power consumption)
on newegg.. any Powersupply (PSU) under $100 is not what most people use.. theyre probably ok.. but like mentioned in many other threads.. its best not to skimp on buying a powersupply as ultimately it feeds all your components the power they require. Preferably go for one inbetween $100-$200 range. i would say something like this one..
Newegg.com - OCZ GameXStream OCZ600GXSSLI ATX12V 600W Power Supply 100 - 240 V CB/CE/CSA/UL/FCC - Retail
Your welcome