I don't know of any real security systems that don't have an "immoblizer" as you like to call it. Every security system should have an ignition interuptor. The engine will be unable to start until you disarm the security system with your remote. The ignition interuptor is the main security feature of most security systems, otherwise your securty system wouldn't make your car very secure. Once the alarm is armed, you can't start the engine until it is disarmed or remotely started with the remote control.
Your security system should also be hooked up to a hood pin switch as well as your door and truck pin switches. If anyone tries to break the lock on your hood latch, to cut your electrical system (which would disable the security system), then the hood pin switch will activate the security system.
Remember, the installation is just as important as what brand and model of alarm you buy. There are lots of different ways to wire up a security system so it will work, but a good installer will correctly wire everything the best way, so that it is dependable, and doesn't false alarm all the time.