That is pretty drastic, sending back a computer for lack of one program, but you shouldn't have to because from what I can find YES this will run on Vista.

If you find that it does not there IS an alternative;

Open Office

It IS compatible with Vista and it is FREE. It's features noted on their website are :
WRITER can of course read all your old Microsoft Word documents, or save your work in Microsoft Word format for sending to people who are still locked into Microsoft products.
IMPRESS is a tool for creating effective multimedia presentations you are free to use your old Microsoft PowerPoint presentations, or save your work in PowerPoint format for sending to people who are still locked into Microsoft products
MATH is OpenOffice.org's component for mathematical equations
DRAW - from a quick sketch to a complex plan, DRAW gives you the tools to communicate with graphics and diagrams.
CALC is the spreadsheet program you are free to use your old Microsoft Excel spreadsheets, or save your work in Excel format for sending to people who are still locked into Microsoft products
BASE includes a full version of the HSQL database engine, storing data in XML files. It can also access dBASE files natively for simple database work.