I want to use OutputDebugString() in my application and then have the option to show it in a separate viewer when the application is deployed in the field.
GExperts has a debug viewer and a unit you add to your application that will do this for you, even in XE2 Starter. See the DebugIntf unit and the GExpertsDebugWindow.exe application that it includes. These work under XE2 Starter (and pretty much all other versions of Delphi).
GExperts also includes tons of other IDE and editor enhancements that are great, and of course they've been around forever, so they're pretty solid tools.