I resized them for you, but gave you a few options, in case one is more suitable than the others.
First there's one where I shrank the entire pic. You see everything, but it is small:
Then there's the one where I cropped it to show just the pony. You don't see everything, but the pony isn't as small:
Then there's the happy medium, some of the background, but not all of it:
Whichever one you choose, you can upload it to your own "My_Uploads" (so I can delete from mine).... and then put that in your sig. ^_^