Search inside dta files (text)

I have some files generated by an in house program, and the file extension is dta (data), but the content is just text.
Inside the files there is scanning activity logs, so pretty much it is really a log (should have said that from the beggining)
Anyhow, my problem occurs when I have to look for something specific. We have about 100 of these files, which are pretty much constantly updated. Every once in a while I need to check one by one to find a specific number. I know that Windows XP can search inside text files, but it won't search inside dta files. Is there any way that I can set it up to search inside those files?
It will probably save me at least 30 minutes each time I have a support call.

Windows grep sounds cool 4 u
official GNU port
http://ovh.dl.sourceforge.net/source...rep-2.5.1a.exe
One with a GUI
http://www.wingrep.com/download.html