Hey, you say you're still on XP, what about content search for XP?

If you have files that are registered properly on XP, Windows knows how to search them already.  What if you are editing files that XP doesn't have registered or the file doesn't have an extension so it can't figure out what to do. 

There is a registry tweak that lets you search files that are unknown to the OS.   Yes, you could use a "real" OS like Linux that lets you grep the files or you could load Cygwin and use grep from there, which I have installed, but XP will also let you search unknown file types with an easy registry tweak.

Run regedit.exe from the run option in the start menu or start a command window, and run regedit.exe from there.   Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\ContentIndex and create a DWORD value with a name of FilterFilesWithUnknownExtensions and a value of 1.

Exit and it should start working.  You might need to log out and back in.  This also works on Windows 7.
Enjoy!    (adding standard disclaimer, be careful, editing the registry incorrectly can render you machine dead and you may not notice until you reboot.)