I think 65nm technology is as far as you can go with the 965 chipset, but I'm not certain.
This I do know, the E7500 is 45nm, and essentially a brand new release. Only boards bought within the last 6 months are likely compatible with it without a BIOS update.
http://processormatch.intel.com/CompDB/SearchResult.aspx?Boardname=dp965lt I saw the same compatibility page for your board that you did, and it looks like you're out of luck. The newest CPUs that will work are the E21XX Pentium Dual Cores, and they're not as good as what you have.
Other board manufacturers may have offered BIOS updates for CPU compatibility with this chipset beyond that of Intel, but that's sort of a moot point.
It's just a thought, but those Conroe C2Ds are notoriously good for overclocking, You might reverse your thinking and replace the board, not the CPU. I'm pretty sure that most P45 chipset boards are backwards compatible with your CPU. If your were to buy a Gigabyte or other non Intel board, the BIOS wouldn't be locked, and you could overclock the E6600.
Then, even if you blew it up, you could always run a 45nm CPU in the later board.
I'm the voice of absolutely no experience, but I think that 3.0 GHz should be easily doable with your processor. (Or so I've heard)
This is the CPU support list for a Gigabyte GA-EP45C-UD3R ;
http://www.gigabyte.us/Support/Motherboard/CPUSupport_Model.aspx?ProductID=2954&ver=#anchor_os You CPU is listed. This board is a very popular model. Other Gigabyte P45 boards should support the same CPUs. The P45 is essentially the successor to the P965 chipset, hence the reason why I'm suggesting it, Your DDR2 would plug right in. Newegg has this in stock;
http://www.newegg.com/Product/Produ...4 1070509908 107172615&name=Intel P43/P45/P55, for 90 bucks. (Some P45 boards take DDR3, you gotta watch).