Open Office will happily open Excel files. You may have to play around with the formatting etc, but it will certainly import the data from an Excel spreadsheet without any problems.
First, go to the north pole. Ask for jimmy, if he isn't there, ask for fred. Either one will give you a pamphlet. Inside is a floppy disk. Bring it back to your computer. You have 24 hours before the...
Usually there is no need to convert, since Open Office can read excel files (except Open Office probably will have problems with macros). If you have Excel 2007, then save the file in Office 2003...