In my experience the North American versions of pretty much every Disney feature length cartoon come with a Spanish option. Off the top of my head: Dumbo, The Little Mermaid, Cinderella, Aladdin. I'd have to check some of the others (which I can do if you're really curious and ordering them from outside the US).
Picture books we have in Spanish: Green Eggs and Ham (love!), The Cat in the Hat, One Fish, Two Fish, Red Fish, Blue Fish (this one is only an "ok" translation and a bit awkward to read if you aren't fluent), The Places You Will Go. I've ordered Big Dog Little Dog but it hasn't come yet. We also have some board books that wouldn't be very great for a 4 year old but that my daughter loved when she was a baby. If you search Amazon.com you can find a TON of Dr. Seuss and P.D. Eastman books translated into Spanish.
A pretty fun Spanish movie is the Me Gusta/No Me Gusta video:
http://www.teachersdiscovery-foreign...20142%20V00024 It's been over a decade since I've watched it so I can't vouch as to how appropriate the content is for preschoolers, but my high school Spanish class LOVED it. You can see a clip from it here:
http://www.youtube.com/watch?v=TKJYrV4rFQ0 That movie guaranteed that I would never forget how to use "gustar." I'd like to get it for my daughter but I have no idea where to find it...