I suspect that Windows 98 and Vista are too many generations apart to
hope for any coordination between them.
I find sharing anything on an older Windows computer with Vista be a
real pain in the ass, and somewhat unpredictable. To share a printer in
an earlier environment with Vista, first make sure they are both in the
same workgroup, MSHOME, WORKGROUP, YOURGROUP, or whatever. Then set up
the printer under Windows 98 as shared. Beyond that it gets dicey, as
you've seen. The easiest way with Vista is to Add New Printer, "search"
for printers, then enter in the name of the Win98 and the printer share
name if and when the Vista computer does not find any printers. The
format is something like: \\win98computer\Deskjet812C . If that does
not work, I do not know what to say. Vista was not bron right... Ben Myers