When i build a new system, I build it NEW. I would be replacing harddrives with SSD. I would be fully upgrading from a DDR2 system to a DDR3 system, so new mobo, CPU, RAM, video card, SSD, and well i could probably keep my PSU. And I don't like to go cheap on my parts. While I get AMD is cheaper, I like Intel. I don't think $1000 is an overestimate by any means.
Oh and my current system runs CS:GO at 70-100 FPS (only cuz i cap it at 100) in CMM and 50-100 in our pub. It is by no means unplayable, as I still kill a lot of people and keep a decent K:D. I just thought a new vid card would help a bit for a cheap solution for a while. From what I remember also, a Q9550 blows away a Q6600 performance-wise. It was the highest end CPU besides those ridiculously priced Extreme Core2quads for like $900-1000.
I will give building a new system some thought though. If I can scrounge up the cash and talk my wife into it. Probably neither happening anytime soon.