For SBO, there is no need of any operating system on SBO PC/Server; because SBO software is integrated with one of Linux’s OS, i.e. Slacko Puppy Linux. If any operating system exists on SBO PC/Server, then also there is no problem as both the systems can run side by side.
Also, if the same PC/Server is used to burn bootable SBO Pen Drive/CD/DVD, then it is better to have Windows operating system on it.
Please read following step by step guide to see how to install & run SBO.