What do I need to buy ? New User Help


I have recently purchased a home and I am eventually planning to have complete home automation setup. I have been reading multiple forums and reading up on Z Wave, Zig Bee et all, but I am still very confused. I know . I also bought an Iris system that I have not opened, so I can return it.

My first priority is to have some basic home security. My home is pre-wired for an alarm system by the builder. I can see the recessed sensors for doors and windows are already setup. I assume these are wireless sensors that operate on the 433 Mhz band (but I am not sure). There are no keypads in the house. Right now, all I want is a system that I can slowly build on.

From what I have been able to gather, I will need a keypad that I will need to install which can beep/alarm when any of these sensors are triggered. Is this correct or do I need anything else ?

Also, I want to have a keypad that can communicate with Vera. Are there any models that I should look at ?

I understant that this is a basic question, but the information available is so vast that I cannot make sense of it without purchasing any of the items. And I want to make sure I purchase something which solves my immediate need. After that I can proceed with building the rest of the system.

Thanks in Advance

First thing to decide is zwave or zigbee.
in US zwave seems to have more penetration. i have vera2 which is a zwave device.
When i bought the house 2 years back the house was wired with some old security system but was disabled by the company who may be monitoring it before i got the house. After tinkering with it figured it out and connected the disconnected connections and now it is working.
Aside from that i had done my homework and already started with vera2. i started with a schlage deadbolt lock and a thermostat. Then added some light swithches. later added a motion/temperature/light sensor. i am still building it but the point is i started with the idea of home automation and may be security/alarm was a secondary requirement. i may extend the system with some more outlets and switches and energy monitor and then thing of water sensors and stuff like that at a later date.
There are a lot of systems out there, i went with vera because of no recurring cost if need be and huge forum community.