I want to spend around $350, but less is always good.
 
I want a quad.
 
I'm putting the CPU in a Shuttle SG33g5. This means I have some heat constraints from the small size and heatsink-based CPU cooler.
 
Which means I probably can't/won't overclock the chip much or at all.
 
I've been considering the Q9450 and the Q6600.  
 
What should I go with?
 
Thank you!

Q9450 is faster and cooler at stock, so if you're not overclocking, that's the better choice out of the two.
 
Why not the Q9300?  Its cheaper, more widely available, and still a bit faster than a stock Q6600.

 
IIRC i counted it out due to the smaller cache and i think the 9450 is only 40$ more or so?

Q9450 will cost more, but should run cooler and has SSE4(new video encoders are starting to take advantage of this). That would be my pick in a small case(assuming the board supports 45nm and fsb 1333, edit... there site says does. so good to go).

If you are not overclocking the Q9450 is faster to start with.

The Q6600 has a lower FSB so its easier to overclock without stressing other parts, but again small case may hold that back.

---------------
http://tinyurl.com/26uxxb - Core2 Temp Guide
http://tinyurl.com/cj3pw - VGA power use

 
Why is the smaller cache relevant if its still faster than the q6600?

 
(as compared to Q9450)
 
i dont upgrade very often.. my current main computer is from 2001, so i dont mind spending a little extra.