How big should pictures be in paysites?

[housekeeper]

I offer my images at 1280 x 853, my script re-sizes to medium as well which I set at about 940px length, I don't see a need to offer smaller ones in the members section. 1024 length has become pretty standard for preview, though I offer 900. I believe the other posters are correct in that 1600 wide or higher is being used, but personally I don't see the need, at least for now.