Thanks,  the site says it takes either ECC or Non ECC but they suggest/offer ECC, Registered as compatible.  Now my question is, is ECC fine or does it have to be "Registered", "With Parity" or will "non-registered ECC work?  Just from reading around, I have seen that RAM can be ECC but not "Registered"
Anyways, more on topic.  I tested the sticks and they are all good, it is just the forth slot that is bad on the Dimension 9200 C2D.  I still have quite a bit of time on my one year warranty so I will call Dell tomorrow.
Anyone know a hot deal on RAM with these specs that is ECC, Registered