Help with using one grid to switch between two different data sources!

Question

I made an app that displays data in a data grid from local xml files. What I want to do is be able to select another data source from a drop down box that will display in the same grid, but not at the same time. The second source is coming from a remote server. Basically, right now i have two separate apps that i want to combine into one app. I have code for both but now i am having trouble combining the two. Let me know if you have any suggestions. Also let me know if seeing source code will help. Thanks