Microsoft Excel 2007 does not have the save as Lotus file option. As such there then is not way to import Excel 2007 files easily. Lotus should give a csv file import option.
I was able to do it by going to an older version of Excel.
Subject: If third-party apps isn’t a problem, take a look at “Notes Import Export Library”
Head over to the homepage of IEL; Voith's CODE :: Notes Import Export Library
Bob, Author of IEL