So even if you purchase the Windows Vista Home Basic edition, your Vista installation CD will still have the setup file for Windows Vista Enterprise. This may be a big time saver when you want to upgrade your existing Vista copy to a different Vista flavor like the Business or the Enterprise edition. Microsoft calls this Windows Anytime Upgrade.
However, the Vista product key that comes with the CD will only activate the edition that you paid for.
Read more about Windows Vista Prices & Release Date.
Related: Windows Vista Coupons for XP Customers