Excel actually has a built in function for this, called "Text to Columns". If your first column contains data that you want to separate, such as last name, first name, just select the column > Data tab > Text to column > choose the separator (comma, space, tab, etc.) and then hit finish. Excel will then expand the column into separate columns with each piece of data, separated by the selected delimiter. One caveat to remember though, is to make sure that you have enough blank columns to the right of the selected column to hold the exanded data, otherwise the data in these columns will be overwritten.
"Maturity is stupid." - Benjamin Franklin