It's time to upgrade my current system as my AMD 4200 was great 2.5 years ago for video processing but just doesn't cut it today.  I'm not going to be gaming much if at all and I'll be doing mostly video and image processing so a Quad is the way to go.
 
I was comparing prices of Q6600/P35 vs Q9450/X38 and the price difference is about $240.  From what I'm reading, they can both easily do 3.6 Ghz and at that speed the Q9450 is faster and runs a lot cooler.
 
I'll be running the system 24/7 so heat and power are an issue but not the biggest issue.
I'm not opposed to paying the extra money for a system that's more stable, cooler, a bit faster and uses less power but that doesn't mean I'm interested in wasting money.
 
Thoughts?

Q9450 just came out, and right now, it's still a bit overpriced (around $140 more than Q6600). So the Q6600 is the better bang for the buck. Q9450 runs faster than Q6600 at the same clock rate, but not by much. Consider the Q6600/X38 combination, you can overclock more than 3.6ghz. With overclocking, a good heatsink is important. Pick one with side mounted fan, high airflow, and high weight. Q9450 consumes less power, but that power rating is at stock, not oc, and you won't save the $140 difference in electricty.

also with a bios update the 45nm quads can run in a P35 board

Yeah, No need for a X38.
The Q6600 will have a Price Drop on April 20th.
Prices have been slipping leading up to that.
 
The Q6600 will be more than fast enough for most.

I'm not sure about that, Q9450 have 8x multiplier, running it at 3.6ghz on a p35 is pushing it. Q6600, with its 9x multiplier, should be okay though.

Doesn't the QX9450 have that new technology that really helps with video  encoding?  
for the life of me I can't remember what it is called but it is the one where intel has version 4.1a and amd has 4.1b (not interchangeable).  Hopefully someone will come to my rescue and remember this and not flame on me for trying to be helpful

SSE4? Q9450 have it too. No need for the "Extreme" ripoff.

Not sure how much it actually helps though, especially on older applications.

Yes, thats what i was thinking of... Thanks dagger
 
I've read that if the application supports SS4, a 30% improvement can be seen.  Don't know how viable this number is cause it was from posts on the forum but if video encoding was the priority of the build --- it should be mentioned  

Another thought, since the Q6700 is supposed to take a major price drop on Apr 20, it would make a good upgrade, perhaps a bit better than the Q6600 because of its higher multiplier. Just a thought.

I'm currently searching for some benchmarks using Adobe Premiere or some other SSE4 enabled application.  A 30% improvement with encoding would be huge!  Worth every extra penny and a few more really.

The Higher Multiplier won't help the Q6700 much.
The Q6600 gets hit Heat/Voltage limits before FSB unless you are into Water Cooling or other extreme measures.

As I said, just a thought, nothing more.

Yes, and its price is still far too high. It performed worse than the Q9450 at stock clock, even without SSE4 being used.

The Q6700 will Drop to a Tray price of $266 which is the Current Tray price of the Q6600 on April 20th with the Q6600 dropping to $224.