What is the recommend max image size in pixels?

I'm guessing that it is 1280x1024 or 1280x960?

Lately I've been cropping to 5x7 inches in PhotoShop, then resizing the image to 1600 across. (and 1143 vertically). If I don't crop my image at all, then I'll submit a 1600x1200. (since that's the size of my LCD monitor)

1600x1200 is okay. Once uploaded, pictures will be automatically resized to 800px wide (small version) and 1200px wide (large version). But the original pictures are also saved.