Memory question, just received upgraded memory from OWC

Hi there,
I have a new 24" iMac 2.8Ghz which we just recently purchased. Loving it so far and it is our first Mac...

This unit comes with 2GB 800Mhz RAM memory. As I have also got Aperture I found performce to slow down a bit, so I ordered from OWC their Samsung 4GB upgrade of PC6400 DDR2 memory which was clearly listed as 800MHz.

So I just received the memory in the mail today, and I read the sticker on the memory which says the following...
2GB 2Rx8 PC2-6400S-666-12-E3 and M470T5663QZ3-CF7 0813

I did not take the memory out of the packaging

From a web search that i did it looks like these memory units are at 666MHz, not the 800MHz that I should have been sold...

I just sent a email onto OWC to their sales dept (too late to call them), and I hopefully will hear from them tmrw.

I just wanted to be on top of the details and to check in with the experts on this forum. What is your opinion of the above ? Is there a 800MHz version of the Samsung memory, or has anyone else ran into a similar issue with OWC before ?

Many thanks everyone...

Thanks to both of you for your great response.
I just wanted to get a good backround check.
Good news then on the memory. I will install it tmrw evening.