Read Only OS

HI guys.

i have 8 PCs Running windows 98 se. so please help me out to make my OS Read only somehow.

i dont know what i want. what i know is i just cant use any anti virus and i cant move on to any other OS.

i just want my windows and my harddisk wants to run as OS works in Embedded Systems.

with this think i can ridoff all viruses and reinstalling isseses.

Thanks.
Love for all.
Ad Rehman
Karachi Pakistan.
0092-333-2312524