Re-sizing MOTD image to resolution of monitor.

[DropDeadRui]

Heyooo!
So me and a pal are setting up our server chain slowly. We're wanting to make a temporary static MOTD for the time being that we can build on, using it as a background.
We've made our own graphics for it but we want the image to automatically fit the motd box no matter the users resolution. Just like how if you have a background image on windows, you can select fit to screen and it will make that image either bigger or smaller and fit.

Any suggestions?

Thanks
Rui