The first thing to verify is if the old printer is even compatible with Vista.  Many of the older printers (and this one is old if it's still the Centronics interface) are not Vista compatible. 

 

If it is compatible then you need a Parallel port adapter.  There are USB to Parallel Port adapters, but I have never got one to work or work correctly.  The best option is a PCI paralle port card but with the "S" model PC you may not be able to find one that will fit. 

 

Best option is to just buy a new Vista compatible printer.  We buy new PC's but try to "make do" with old attachements such as printers.