I7 920 New build mb / memory HELP???

According to this review it should work fine:
http://www.thinkcomputers.org/index.php?x=reviews&id=93...

Quote:
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Memory:
- 6 x DIMM, Max. 24 GB, DDR3 2000(O.C.)*/1866(O.C.)*/1800(O.C.)*/1600(O.C.)/1333/1066 Memory
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Apparently using the 1600+ memory timings depends on the QPI of the processor.
This also apparently (according to the review) means that you need to OC the processor to match the timings of the processor (Page 6).
If you don't intend to fool around with overclocking then perhaps a standard 1066 or 1333 memory would be a better fit.

Though please keep in mind that I haven't tried this myself, i bet others on the forum can give a better suggestion.

So, it works fine but you won't reach the potential of the memory unless you overclock your processor.

So the memory I have chosen is an overkill since I do not plan on overclocking? Would the 1333 would be a better choice?

As far as I can tell i would be overkill.
If you don't overclock then you would "only" be running the memory in 1333 anyway.
Though in another forum post regarding another Core i7 920 build they suggest using 1600 memory so I don't see why not.
If some day you want to overclock a bit then it won't hurt to have the memory speed for it. Your motherboard supports it.
1800+ is a bit overkill in my opinion though unless you get bitten by the OC-bug.

If the budget supports it then go for it.