Just wondering what would be a good arrow weight for whitetails?  I am shooting 51 lbs @28.

IMO, 500-600 gr.  I'm shooting 51 @ 26 and like something about 560 gr.  My bow is quiet there, performance and trajectory are still very good.  I can go to about 600 with this bow before it starts to slow down more than I like.

Somewhere around 10 grains per pound of draw weight works pretty well. A little more or less is fine. I shoot 510 grains (11.09 gpp) from my 46# Kanati and it blows right through whitetails. The same arrows cut 1/4" shorter work fine out of my 52/53# bows.

Like was mentioned above, 500gr. or so. You can use less, and I'm sure someone will come along soon and tell you to use 400gr., but the heavier arrows will be quieter,more efficient,less handshock and will yield better penetration.

I use 420 or so and blow right thru them - 53#.
Bow is quiet with no handshock.
Killed a large mature cow elk with the same setup.

Well....this weight creates a quieter bow is only partly correct.  A well tuned arrow to the bow will not be noisy, and may very well be quieter than a much heavier one that is not particularly tuned that well.  

I've been doing this for a long time and find a well tuned arrow of even 8 grains per pound will not be "noisy" and may be the best for the job.

I use arrows that are around 460 to 480 grains and my bow is very quiet, and the arrows normally pass through whitetails.  The key to whatever you shoot is that it hits the target while flying perfectly straight, with all the power on the tip of the broadhead. If that happens, you have no worries.

Perfectly said, George!