Can someone tell me whats better a Q9450 or a Q6600, i want to over clock as well. Which one is better in gaming and can last for 2 years?

Overclocking: Q6600
Gaming: Marginal difference, but Q9450 at stock and Q6600 when overclocked
Last for 2 years: Both.

The Q9450 will be the better choice if you are skilled at overclocking and can shell out for a board that can get higher FSB overclocks, since the Q9450 is likely to be more limited by the boards FSB max while overclocking then the Q6600 is, which is why people say the Q6600 is the better overclocker.

Q6600 = sub 200$ at certain places now. was 189$ at frys a week ago
Overclocks like a champ as stated in previous posts because of its 9x multiplier
 
Q9450 = faster at stock, can decently OC also but limited by its 8x multiplier. get this if you're going to do multimedia editing because of the SSE4.1, a lot faster than the Q6600 at this task.  
 
now, you can also add in the Q6700 into your question as well
 
Q6700 = recent price slash of around 50%. can find it on newegg for 299$ other cheaper at other places such as directron (only 289 there with no tax/shipping). 2.66ghz stock but has a multiplier of 10x which equals a higher OC then the Q6600.
 
if you're on a semi-limited budget, i would get the Q6600, its blazing fast. i have both the Q6600 and the Q9450 in two computers so yea. Q9450 cost a little bit more though. If i had a choice between the Q9450 and the Q6700, i would go with the Q6700 because of its 10x multiplier.

I think it comes down to what kind of motherboard you are looking at. If you can't afford a board capable of 1600 MHz FSB or you are not skilled at overclocking and are afraid of pushing a 1333 MHz board to 1600, get the Q6600 or Q6700, they start at 1066 FSB and easily overclock to 3.0 and 3.2 with a push to a 1333 FSB which you can find fairly cheap motherboards for. If you don't mind shelling out the extra for a 1600 or are comfortable OCing a 1333 go for the Q9450. Also if you are considering the Q9450 consider the Q9300 as well. If you want, this is a really sloppy comparison but as far as being counterparts, the Q6600 and the Q9300 are 65nm vs 45nm counter parts as well as the Q6700 and the Q9450. The latters are just 45nm and run at higher native FSBs. If you are strapped for cash or are sticking to a budget go for Q6600/Q9300. If price isn't too much or your budget allows for more in the CPU area, go Q6700/Q9450. Just remember that the 45-nm are gonna cost you more in the motherboard area as well if you arent' comfortable with overclocking. Good luck to you!
 
EDIT: Also consider how much 200 MHz more means to you. If I remember correctly, the extra multiplier on the Q6700 and Q9450 will get you to 3.2 GHz, rather than 3.0 GHz from the Q6600 and Q9300, yet the Q6700/Q9450 cost around $100-$150 more than the Q6600/Q9450.

iKuno,
 
You never said how much you wanted to spend.  If price is no limitation, then the Q9450 (or Xeon X3350) is the CPU to get if you are looking at "future proofing" your system.  The Q9450 overclocks just as well as the Q6600 with the right motherboard.  My 780i can overclock my X3350 easily to 4Ghz @ 1.42V.  But, for practical day-to-day application I run it at only 3.0Ghz.
 
So, what are the advantages and disadvantages to getting the Q9450/X3350 over the Q6600?  Here you go:
 
Advantages:  
 
Higher 1333Mhz FSB (Q9450/X3350) vs 1066Mhz FSB (Q6600)
 
12MB L2 cache (Q9450) vs 8MB L2 cache (Q6600)
 
Prefetch instruction SSE 4.1 (not included with the Q6600)
 
Uses approximately 100-140 watts less power under full load versus the Q6600
 
Runs at cooler temperatures; making air-cooled solutions an easy decision
 
Disadvantages:
 
Voltage tolerance:  It is now well known that the older Kentsfield CPUs have a higher voltage tolerance (1.6+ volts capable) whereas the 45nm Yorkfield and Wolfdale CPUs have a ceiling of about 1.55V. Some new Penryn CPUs owners who got a little too aggressive in overclocking have fried their CPUs.
 
Multiplier:  A lot of complaints in regards to the Q9450/X3350 only having an 8x multiplier.  I have had no issues or limitations in regards to this, but have heard other folks having "FSB wall" problems that are intrinsic of a lower multiplier when overclocking.
 
PRICE!!  The Q9450/X3350 will run you around ~$325-350 versus a Q6600 will cost you "only" about $200.   Intel just slashed the prices on the Q6600 and Q6700 processors; you can get a Q6700 for about $250 as of 22 April.  I believe the Q6600s are now going for around ~$200.
 
Other thoughts:  If you really want a voltage-durable CPU, and don't care about SSE 4.1, the extra 4MB of L2 cache, or the power consumption, then get the Q6700.  It comes with a 10x multiplier (versus 9X multiplier of the Q6600) and is very durable and proven.
 
In both synthetic and real-world benchmarking both Kentsfield and Yorkfield CPUs perform almost identically (albeit, the Q6600 runs much hotter and uses more power).  There are a couple multi-media programs that do better with the Yorkfield CPU, but not by a large factor.  And since no programs that I know of take advantage of the SSE 4.1 prefetch instruction, it all comes down to how much money you want to spend.  For now, the Q6700 is the best bang for the buck in terms of raw horsepower and overclocking potential.  I own a X3350, but couldn't justify to someone to spend an extra $100 if they are on a budget.
 
If future-proofing your system for the next 2 years is of the highest concern, get a new Yorkfield processor or just wait for Nahelem to be released in Nov-Dec of this year...

I agree with all the Q6700 comments.  Since the price slash it's the best deal going right now for quads.

I'd go with the q6700 at or below $300. The better mulitplier will make it easier to OC and put less stress on your mobo, since you won't need to raise the FSB too much to get to 3-3.4 gHz.

 
Unfortunately there are no codecs that use SSE4 yet

I believe that DivX does, as I've seen benchmarks of it with SSE4 enabled.

^Only the alpha/beta's
 
Divx isnt really considered to be a popular or efficient codec these days anyway...despite the huge hardware support.
 
SSE4 will make its way over to xvid and x264 eventually... the developers just need to get their hands on a CPU with sse4 to test with

 
OK let's get this cleared up before it goes any further. The Q9450 has an 8x multiplier, while the Q6700 has a 10x multiplier. Q6700 gets my vote, and if you're on a tighter budget then the Q6600. Q6700 is only $289 w/free S/H at Newegg right now, while Q6600 is $225 w/ free S/H.

Note that the Q6700 can be taken to 4.0GHz with a good air cooler, while the Q6600 usually will only hit around 3.6GHz or so at most.

NewEgg had an Abit X38 on sale for $138 AR shipped.
That would be a killer board with the Q9450.
 
But as others have said, the Q6600 is cheaper and will OC better on lower end boards.  The Q9450 will be more expensive and you will need a high-end board to take it past Q6600 performance.
 
The Q9450 does run much cooler if that matters.

^Ninjawithagun already said most of what I said. Just wanted to "give credit where credit is due"
 

^Just like I said, Q6700 FTW!

I got my Q9450 from Microcenter for $306 shipped.  At some point I'll mildly OC it, probably depending on whether/if I need to get new memory.  I've got 2x1GB of Crucial Ballistix DDR2-1066 that would not work reliably on a GA-P35-DS3L, that seems to be fine on my Abit IP35 PRO.
 
Edit: I selected the Q9 over a Q6 primarily because of power and heat issues.  I prefer greater efficiency.  So far, I've been happy with it.  When active but still mostly idle, my rig sips about 150W, but I've got most of the power saving features turned on.  That's according to my APC UPS; I still need to plug it into my Kill-a-Watt for a better test.

I prefer not to overly stress my motherboard, so I'd go with the Q6600. Better yet, the Q6700, as others has mentioned. Either way, the Q9xxx and Q6xxx will not disappoint, and when OCing is considered, they both have their ups and downs. What's important to the buyer is what really counts.