.....from an Excel CSV file into my Excel/VB Macro application.

Briefly, I have developed an Excel application that runs as a macro -
completely hiding Excel. I have another application (not written by me) that
exports its data into a comma delimited file readable by Excel. I wish to
extract certain columns from that particular file, compare it to the data
that is already stored in my application, updating the fields as necessary.

My initial idea is to completely load this huge file into a worksheet within
the application, strip it down to the necessary columns, and then
programatically compare data, inserting and deleting where necessary.