Image height resizing to screen size.

Hi, I have an image on my website i want to have it so it resizes to any monitor. It does for it's width but i want it to for it's height. Here's my website www.creationindex.com. The image is logospining.gif. It's the one that starts in the middle and spins toward you. I'm not done with the image i just need to know how to get it to resize to any monitor. The image is 1950x1200. You can get the idea with what i have on there. Thank you.

I cant see any image which should float vertically too....

it's the one right in the middle of the page. You might have to scroll down on some monitors. Thanks for helping.