I understand you're on Windows an thus the Win32::OLE recommendations above are dead-on. I've done this too with Perl (for Excel specifically) and it does exactly what I wanted.

However, if you were on Unix, you could just use 'grep'. grep -A and -B will give you lines before and after your match and grep -l/-L will print filenames if they do or don't contain your match, respectively. Why reinvent the wheel?

For Windows, have a look at:

http://downloads.sourceforge.net/project/unxutils/unxutils/current/UnxUtils.zip

This contains grep and all the Unix text-util favorites for Windows boxes. I find it INVALUABLE!!!