Would this CPU work with my Motherboard?

http://www.asus.com/Motherboards/Intel_Socket_775/P5LMX... < YES. And Yes you will notice a huge speed improvement. The core 2 architecture is much more powerful and efficient than the old celeron/pentium4 D.

The E6600 Conroe will give you about a 50 - 60% increase in CPU speed. I'd estimate overall system improvement of maybe 30 - 40%.

You will get a big increase in CPU speed, so-so increase in memory i/o because of the faster FSB freq, and no change in disk or video i/o.

Make sure you get the 2.4 GHz E6600 Conroe, not the newer 3 GHz E6600 Wolfdale. According to the website, the motherboard does not support the Wolfdale CPU.

Thanks for the reply guys ! I also noticed to avoid the 3 GHz , which is very new  

So you really think my overall improvement would be 30-40% ? That would be great.
And also I'm sure you can confirm that my GPU is bottlenecked quite a bit isn't it ?

Oh and I will probably buy it without a cooler, which one do you think I should buy for it ? Something very cheap that just does the job,
although I might OC it if it can be. (I dont want to use my Celeron heatsink, it is awful )

P.s. I could look to play a bit of Starcraft 2, which atm cant be played above normal settings, but here on tom's I recall they showed that the 9800gt can play it on ultra fluently, which is another reason I think the CPU is holding the PC back.

well i have an 8800gts, which is a little slower than your 8800gt, and i got a huge performance boost after upgrading from an athlon 64 3500+ (similar to your celeron for gaming) to my e6600. Then i oc'd it to 3ghz and saw even more performance increase with still the same vid card. Mind you im only running 1440x900 resolution so my vid card isnt too restrictive. Newer games arent running that great now and a GPU upgrade is needed for me. I also have my cpu at 3.2ghz now and will try to get it to 3.4ghz. That will be a 1ghz overclock. Your motherboard is limited by a slower FSB so overclocking would be more difficult for you. should still be able to overclock a bit though.

So you have the same setup, awesome. My resolution is only 1280x1024 so that would be fine too. I will not be playing any new games at all, nothing that can be played on the Xbox for example. But as I said I probably would try some PC exclusives a bit more.

But overall great news, I will definitely scour ebay to get one. Only other thing would be to get a decent cooler, I doubt I should get the stock e6600 one, Im sure it would be worse than any midrange 3rd party one.

I was talking about purchasing the stock e6600 HEATSINK.

Another thing that I thought about was since my motherboard would have to run at 1066 FSB , would that mean I have to ensure my ram can run that high too ?

the prices of the q6600 are still pretty steep. even second hand they can go for as much as 70 pounds and new for 120
which is quite a lot for a cpu that has had the potential to be abused due to its oc ability...
you may get more piece of mind going for something like a q8300 or q8400 for 80-130 pounds if your motherboard can handle it... very similar price but more performance.

I am grateful for your guys's response but can you first read the thread ?
I am NOT talking about q6600 but E6600 (The 2.4 one)

And I am not looking into buying a motherboard, I just want to get a cheap CPU that would boost performance.

my bad. to little sleep for me...

It is ok, I am grateful for all the responses. Only thing I have yet to figure out is if my RAM can work on the higher (1066) FSB. And as far as I can tell the system is running at 533 FSB (looking at my current CPU)

ram doesnt really care what the fsb is as long as it has a jdec/spd multi to match it up to. even if your ram is 800,667 or 533 you will be able to run it at its rated speed.
just go into the ram timings and you should have a few ratio choices just set it to the 1 that gives the fastest rated speed for the ram.

Well I checked on the motherboard's website and it says that it supports up to 667 RAM, which I'm pretty sure is what mine is.

So it would run at no problem ? At 667 ? I'm not sure what timings it is capable of, obviously the lower the better but still wondering.