A few weeks ago I posted a way to use PowerShell to find in files. This is just an extension of that post to show how you might open the results of your find in a program.
Select-String is a cmdlet that will search files or strings, sort of like grep in Unix or findstr in cmd.exe. If you use the Get-ChildItem cmdlet, you can specify the -Recurse switch to retrieve subdirectories and the -Include switch will only include the file types that you specify. Then you can pipe it over to Select-String.