Filter External data
 

I have connected an Excel 2007 worksheet with an external text file. The
text file contains extraneous lines of data that I'd like to filter on
importing (as opposed to a workbook filter, which will not filter the rows
out of calculations). The extraneous lines contain only 2 comma-separated
fields each, while the lines of interest contain many more.

How can I specify to import only the lines of interest when refreshing?