RAM Usage in Win 98

This may be naive…but: can anyone tell me the “optimum” amount of RAM to put in Workstations running Win98SE, please? I’ve been told that “98 won’t use more than 128MB, so why bother with more?”. With 25 PC’s on a WIN2K LAN, I configure all that have more than 64MB RAM as “Network Servers”. Most PC’s run Word/Excel and our own, old COBOL prog in a DOS window. A few need more RAM (???) to help with Graphics programs.
But how much more…..?