if you have photoshop, change image size and then save for web.
You can email it to me if you need ill do it quick...im on photoshop and illustrator all day lol
Here's a free link I got from a member a few years ago. Its really easy to use. Just follow the steps from 1 to 4. On step 2 change only the width to 400, the rest will change itself. (you can try 500, I just never had cause that is what I was told to do). I did notice if you resize and dont like it, undo before you resize again, if not it will resize that newly sized pic. HTH
my comp came with some picture software and i just click on the image bar then scroll down to resize then type in 500 on the top pixel amount field and it automatically fills in the bottom field...
took me a couple times to figure it outm too