Help me find the right corsair ram for my new 650i system!

I'm building a new system, core 2 duo, 650i motherboard, but what RAM should I get?

Corsair's website gives me a long list of supported modules.

I guess the three I'm looking at right now are:

TWIN2X2048-6400C4D ($304) *Before $40 MIR
TWIN2X2048-8500C5D ($369)
TWIN2X2048-6400C3DF ($477)

Is the price difference between the 8500C5D and the 6400C4D going to be worth the extra speed (and higher latency)? I've been told the 6400C4's will run at 8500C5 anyway - is this true?

And finally, $477 is a lot of $$$.

If latency wasn't critical, wouldn't the 8500C5D be the better option?

That has a higher latency but is faster.

Price is certainly a factor, but most importantly I don't want to waste money.

I think $477 for ram is wasting money. Like I said, I've been told that the 6400C4 sticks can make it to 8500C5 - if this is true than the cheaper modules are the obvious choice.

I'm mostly going to be gaming, and video editing, maybe some photoshop work too.