Cannot Open Excel Document

I recently purchased a new laptop computer with Windows 7 Home Premium.  I brought over my data files from an XP/SP3 machine on an external hard drive, and I copied the files onto the new laptop.

I subsequently tried to open up an excel document I brought over on the external hard drive.  Even though I have Office 2003 installed on the computer, and each of the individual applications is operational (Word, Excel, PowerPoint and Outlook), the excel document I tried to open would not open.  Instead, an "Open with ..."  window appeared that asked me to suggest a program that could open the document.  This window provided a list of possible programs that should suggest could open the excel document.  But none of them is Excel!  Furthermore, if I select “browse,”so I could search through my available programs to find Excel, none of the Office programs appears.  The main Microsoft Office folder doesn't appear either.  Furthermore, the excel document even shows the correct .xls extension. 

How is it possible that a Microsoft system can't recognize the extension of a Microsoft document?

Can anybody help me solve this problem?

Thanks! 

laserguy