Irfranview comes to mind. Small, fast and surprisingly capable given the first two. There's also virtually any web browser if all you want to do is view the image. GIF was one of the most popular image formats in the early days of the web and as a result all the major browsers will support viewing GIF images.
My Worship Team leader creates the monthly schedule using Excel, and the email attachment has a gif file extension which my computer won't open. I see all sorts of programs on the internet that I can download to do this, but I'm hesitant to download something I'm not familiar with. Can you recommend a safe program for converting gif files into something Microsoft word will open?