Replacing non-compliant memory with ?

This is a remake of the other thread I started on memory. I guess I titled that thread wrong.

Anyway to my problem.
I currently have a GIGABYTE GA-P35-DS3P with Corsair (twin) DD2 800 XMS ram. Problem is the Corsair XMS 6400 is NOT listed as compatible with my Gigabyte MB and I didn't notice the memory was excluded from the approved ram list when I ordered it. And yes I do have problems with this ram and my MB. I am getting write failures when doing memtest. I ran memtest because every so often, once or twice a day my computer would give me the BSOD.
After some reading I did in fact learn that write failures were a problem with Corsair XMS 800 ram and GIGABYTE GA-P35-DS3P MBs. So in short I need some more ram.

Logically my question is which?
I see Newegg has the Corsair XMS 1066 for $123.00 after rebate and it is listed as acceptable for my MB. Would this ram oc much higher than the Corsair XMS 800 that I need to replace in my MB? Is there really much difference with these 2 memories types seeing the XMS 1066 has looser timings than the 800? Kingston is also listed for 1066 in my MB, would this be as good a choice?
Lastly; what is the difference between Corsair CM2X1024-8500C5 and CM2X1024-8500C5D (D at the end)?

Thanks,
Mike

tbh it sounds like you were unlucky and recieved a faulty set of memory.ive found that the approved list is only a guideline for modules that have been tested.most any memory should work with your mb despite its not being on the qvl.the only case of incompatability ive found was with modules that required more voltage than the mb could provide.i would test your modules in a different rig and rma them.
if your looking to move onto a set of 8500s i would check out the crucial tracers at buy.com($70-80).
the d in c5d denotes the dominator series.
good luck Mike!