Hey,
I've had the same motherboard, the DG965WH for more than an year now.
I know it cant be overclocked, but its really stable and a capable performer at stock speeds.
I feel you'll be much better off to just wait for a couple of months, and buy a new CPU when your new motherboard arrives.
If thats not feasible, the current choices you have are any LGA 775 CPU based on a 533/800/1066 MHz FSB.
The Quad core Q6600 may not work, if your board revision is below
AA# D41692-305. You can check this number from the BIOS, or from within Windows using Intel Desktop Utilities.
Please dont attempt to use the E6550, it may wreck your stable and running motherboard.
As far as the 946GZIS motherboard is concerned, it was specially designed to handle 1066FSB, so theres no surprise that the E6300 worked on it.
Anyhow, I hope this helped,
Good luck
Forgot to mention that u can refer this site to clear things up:
*processormatch.intel.com/CompDB/SearchResult.aspx?Boardname=dg965wh
But it may further confuse you.
The spec# of the CPU can be found on the CPU box itself, and has to be verified for certain CPUs before u even open the box.
This may have confused u, but its the only comprehensive solution.
refer this site as well:
*support.intel.com/support/motherboards/desktop/dg965wh/sb/CS-026598.htm