Is there a file that is specific to each operating system?

I am working of a batch program, and it is an installation program. I would like it to be able to detect the operating system automatically using the IF EXIST command. Is there a specific file for xp, vista\7 and other operating systems that I could use?

For exaple if exist C:\Windows\filename (GOTO xp) else—(goto—next)
:next
if exist C:\Windows\filename2 (GOTO win7) else (goto 95)

Something along the lines of this.