There are several home automation technologies out there depending on the requirements - many have different cabling requirements. I would recommend DIY kits. They've got a bunch of wireless and hardwired DIY kits that can be used with their inexpensive monitoring service. For a small to medium-sized townhome, a wireless kit may be good for you.
A very good option would be a company called Mile High Automation. They make an integrated system called Home Automation Platinum Package: Whole-House Solution which is sold in almost every where and is very popular.
It's got:

* Omni Pro II Home Automation Controller
* 1 Touch Screen
* 2 LCD Keypads
* 6-Zones of Audio
* 17 Automated Light Switches
* 20 Security Contacts
* 2 Thermostats
* Computer Control Software
* Complete Programming & Support


You can start with just the alarm system and grow it to a fully functional home automation system.

You can also submit your floor plan and can get free estimate plan to implement DIY systems in your home.

Home Automation Products and Services
Free Home Automation Estimate
DIY Home Automation


Cheers
Cody