LINUX For Business Application

I am looking at the possibility of using LINUX as a platform for my core system. There is a network of (200+) outlets throughout M’sia and we are in the financing retail business. If Linux is used, which would be the recommended development and database environment to evaluate? Any suggestion on the data communications infrastructure and are there any real savings, as compared to using the more commercial environments such as Microsoft, versions of UNIX etc.. (especially in the areas of user licensing and implementation/training costs).