embedding excell in an html file

I am working on a website for a client who needed me to embed excell spreadsheets in a few pages.  I have no experience with excell so he simply gave me an object tag  containing the spreadsheets  to copy and paste.  Everything works fine except users with Office 2003 cannot view the actual speadsheets. They recieve an error message stating "To use this Web page interactively, you must have Microsoft® Internet Explorer 4.01 or later and the Microsoft Office Web Components."  I don't even have excell on my computer and I can view the spreadsheets just fine. The settings on my client's pc are corrrect but he cannot view the excell becuase if Office 2003. We know this is the problem because every other PC in the office pulls up the spreadsheets. Is there anything I can add to the code that would enable all users to to view the spread sheets.? I am tottaly baffled because I don't understand the object tag to begin with.  If there is anyone who can help I would appreciate it.