Addition to neileg's advice: If you have titles in the Excel sheet that is linked as a table, it will very likely cause your DB to have errors unless you have a clever way picked out to exclude all titles, column headers, etc. when you run a query based on same.
Also, if I recall correctly, there are limitations on the actions you can take when Excel is your storage medium and Access is your front end. Among them, I believe, is that you have Bloody Hell if you want to add fields to the table through Access. You have to make the changes to Excel, delete the Access table, and then re-link to the Excel to update the fields. (Unless this has changed VERY recently.)