Application.Current results in an appdomain http://msdn.microsoft.com/en-us/library/system.appdomain_members.aspx
Also this should give you the location of the assembly
AppDomain.CurrentDomain.BaseDirectory
I seem to recall there being multiple ways of getting the location of the application. but this one worked for me in the past atleast (it's been a while since i've done winforms programming :/)