any rationale to getting e6600 over e6750?

It's up to you really. The q6600 has 4 processor cores running at 2.4 ghz. The e6750 has 2 processor cores running at 2.66..It makes sense why it would show it ahead in benchmarks.

Certain applications will see a benefits when it comes to Q6600. Mostly applications that are multithreaded will benefit. Multithreaded is a term for creating a program that has the ability to use multiple cores. Video editing programs, 3d modeling programs, some games and other applications are multithreaded..Which means it would see a benefit in having access to a quad core cpu. The future of computing will take a turn of multithreaded applications. Crysis which will be coming out soon is multithreaded...So even though you may have a faster processor..the fact that crysis can utilize all four cores running at 2.4 ghz it will have an advantage..Afterall. two cores can only do so much even if they're clocked faster..But with four cores it can run more calculations at once.

The choice is yours really though..It really depends on the applications you are going to use. In certain scenarios it is better to get a dual core....While in others a quad core is more suited...But one this is certain. As time goes by programs will become more frequently multithreaded. With that turn of events if a new computer is going to last you several years...It'd be smart to invest into quadcore...

Hope that helps ^_^..if you have any questions feel free to ask.

The E6600 loses to the E6750 in every respect.

1) It absolutely does not OC as well as the E6750. The new G0 stepping is a huge improvement in the manufacturing process Intel implemented that lets the chips run faster and consume less power.
Anyone who claims otherwise, is just likely a E6600 owner who paid alot of money for their chip and can't accept that time marches on.

2) Is there a reason why you do not intend to OC. There are many levels of OCing. Example, The E6550, E6750, and E6850 are identical chips. The only difference is the hard-coded multiplier. As a result, running the E6550 at E6850 speeds would leave the chip still running at manufacturer specs. This would not involve any special hardware, create excess heat, or risk your chip or hardware in any fashion.

I leave the overclocking up to the pros. In my build, I am not including any additional cooling or any super high-end motherboard that would facilitate the overclock. To the first response, I definitely appreciate the time you put in to replying, but both are dual cores. I haven't looked at the q6600 at all, only the e6600. I'm keeping my budget right at 1000 including monitor and speakers (not simply the box itself).

Tinkering with clock speeds seems like a road to disaster with my luck, and I don't want to break the bank by having to buy another processor to replace the one I fried by not observing some voltage spec, or something outside the scope of my knowledge.

Minor overclocking isn't that difficult, and should require a voltage change. If it does, most MB's have automatic voltage control that would be sufficient for what you are doing.

Edit: The e6750 is way better than the e6600 in all aspects.

Edit 2: Having too low of voltage won't fry anything, because it just means that the CPU isn't getting enough current. (current=voltage/resistance) Resistance increases as the processor speeds up, hence more voltage required to maintain the current needed.

Here's a question. When did the OP mention the Q6600?

I could of sworn I saw a Q...I did see one e though while the rest of my eyes said q..I was wondering why someone would ask if it was a rational purchase to get a e6600 to e6750..lol..It's not rational at all...

Regarding these processors...get a e6750..I really don't understand why or how the e6600 is still priced higher..It's an inferior processor...

  Your eyes are as bad as mine, but I'm an old fart, can you say the same?

lol..If old is considered 23 then I'm one also...=P...lol..But I mostly blame sleep...Yes!..That's it!..Lack of sleep..I've been up for 28 hors now...lol..