The OS (Operating System) such as Windows 98 or XP, etc., is not the reason you are getting the message.
You probably do not have same versions of Excel on both PCs.
Usually newer versions of Excel have little, or no, trouble reading older versions of Excel documents. But there may be some internal Excel conversion problem that your Excel doc on your one PC is having on your other PC.
I suggest that you convert the file to .cvs and then open it up on your 2nd PC.
In my win98 spreadsheet (excel) there is some work I would like to beable to look at in windowsxp, my computer replys " not conpatable", is there a program that would make it conpatable? thank you for any help you may offer.