Once you have set up a corporation, a C corporation to be precise, you can convert it to an S Corp. All you need to know if how to convert to S Corp from a C Corporation.
How_to_Convert_to_S_Corp.html
In the past, S corp business structure was the only way a business owner could have both personal liability and pass through taxation. Nowadays an LLC does the same job or even better than S corp. The debate of the S Corp vs LLC is gaining more and more notice.
S_Corp_vs_LLC.html