You got good advice from jmen 24 on doing your homework and going to a store like EMS to get educated even if you buy from Walmart later. Also Sunrise Point noted the sale at EMS. The EMS site has a lot of choices by weight and intended use:
http://www.ems.com/family/index.jsp?categoryId=3701091
Two important features to look for:
1. Bindings that are easy to use as well as secure. Having a snowshoe come off in deep powder and then having to take your gloves off to fuss with a poorly designed binding is not fun. What works well in the store may not work well in the snow.
2. A rotating pivot device under the toe that allows the heel to drop when you lift a foot. This allows for shedding of snow off the back, makes it much easier to step up a steep bank and allows the toe crampon to get a better grip.