I recommend giving Faststone Image Viewer
a try. It's a great free image viewer that does display .gif files with animation, and about every other format including most raw formats. Really great program and hard to believe it's free. You can make it the default image viewer in Windows and it's also super fast as well as very full featured. The only reason I don't use Fastone as the default viewer myself is that I like to be able to zoom in on images using the scroll wheel alone (without having to hold down another button). Most other image viewers besides the Windows one and the Windows Live one seem to require holding down a key in combination with the scroll wheel. But I do frequently use it anyway for some of its other excellent features.
Edit: While taking another look at Faststone as I was thinking about this post, I just discovered that it is possible to remap the fuctions of certain keys in FastStone. So it turns out I am now able to use the scroll wheel by itself to zoom which is what I liked about the default Windows photo viewer. So with that adjustment made, now I'm really happy to make FastStone my default image viewer. Also the up and down arrow keys zoom in and out in nice increments and the right & left arrow keys advance to the next photo or move back to the previous photo respectively. Now it's perfect.
I also love the way it opens photos by default into a borderless full screen view without any buttons or menus showing. Then if you want to see some menus, you just move the mouse to any of the screen edges and a different menu appears depending on which edge you bring the mouse to. It's really the best viewer
I've seen and I've tried a lot of them, including expensive ones. Although it has some fairly advanced editing abilities, I do use other apps for serious editing and another nice feature is that one can easily open those apps while viewing a particular image right from within Faststone. So, I mainly like it for it's great viewer functions (and it's ok for very simple editing as well).