What Apple mouse or trackpad is best for navigating large two-dimensional documents? I've been using Xcode on my Mac Mini for a few months with large app storyboards etc. To do this, I need to constantly zoom in/out of the document to see what I need to.

I've increased the size of my monitor to a 24-inch display, but I still find myself needing to zoom a lot.

So, what Apple mouse or trackpad (Mighty Mouse? Magic Trackpad?) will help me zoom and navigate fastest in Xcode and Photoshop?
I don't use storyboards in my development workflow, but my experience with the Magic Trackpad has been vastly superior too my experience with the Magic Mouse. Lion's gestures were designed for the trackpad, so it's pretty much a win-win there.