Upgrade E6750 to E8400 on 680i?

Alright fellas (and ladies, if we have a few checking the forums)

I've got a quick question.

I've got an MSI p6n Diamond - their 680i board. I have an E6750, and an 8800 GTS 640.

My father in-law wants me to build him a computer sometime over the summer. I was planning on keeping my case, HD, PSU, mobo, etc, but buy a new CPU and new GPU.

I was planning on getting the E8400 (once I find them someplace with a reasonable price that is not sold out) and have already purchased an EVGA G92 8800 GTS. I'm planning on getting the second 8800 GTS sometime over the summer to go SLI.

Does this seem like a reasonable plan? Give him the 6750 and the old 8800 GTS and get the new 8400 and new 8800 GTS?

Will my motherboard work with this? I've checked around and it seems like MSI says it's still being "tested," but the news release from November 2007 says that they will be supported. I hear EVGA already has a BIOS revision that works.

Should I be worried? Anyone have any experience with the 680i and the E8400, or the 680i and the G92 8800 GTS?

Thanks. Your help is appreciated.