[Setup]: MinVersion

Format:

major.minor

Default value:

6.1sp1 (Windows 7 with Service Pack 1 or Windows Server 2008 R2 with Service Pack 1)
Description:

This directive lets you specify a minimum version of Windows that your software runs on. Build numbers and/or service pack levels may be included.

If the user's system does not meet the minimum version requirement, Setup will give an error message and exit.