Rather than using the Open command try: Data> Get External Data> Import Text
File.
On the second page of the Import Wizard choose Comma rather than some other
delimiter & you should see that the data preview appropriately separates into
columns. (The teminology may vary depending on version of Excel & I'm going
from memory without having a Mac available to check on, but that should point
you in the right direction.)
HTH |:>)
Bob Jones
MVP Office:Mac