If you want to stay in Excel, you can also use the Microsoft ODBC text driver, which allows you to treat csv files like database tables and run SQL queries against them. You would also need to install the Excel ODBC add in for that. There are some bugs with the installation program for that, so you can just open the executable with winzip and grab the dll and xla from there. And remember google is your friend. I am guessing you don't know SQL either, but if you are serious about data miniing, you should learn it.