Here is a simple home Video Surveillance system that is affordable and easy to use. The unit is made by Everfocus, I have installed 100's of Everfocus units for approx 5 years and they are great. They are an OEM manufacturer who makes these units themselves. Most of there products are warranted for 3 to 5 years. There ECOR brand is perfect for a budgeted home installation.
It has a built in GUI for access through your home network and is very easy to setup for remote viewing to keep an eye on things at home. I only recommend wired security networks unless we are talking about commercial applications. Home wireless networks have not been the most reliable.
You can hook the unit right up to your existing VGA monitor and plug in your cameras and you are in business. One of the best features about Everfocus units, if the Hard drive fails you can buy an off the shelf drive and replace it. No sending it out to get it repaired and waiting for someone else to fix it, which will cost money. Most other manufacturers require you to replace there failed hard drives by them and will charge you big. Most failures are hard drive related because the disks are constituently spinning 24/7.
These units are considered an embedded DVR (Digital Video Recorder) and runs on a Linux platform which runs cool and uses very little power compared to a PC based system.
It also runs off 12 VDC for all home Alternative users.
I use almost all of Everfocus products they are reliable and like I said, I have installed hundreds of there cameras and DVR products for 5 years.
http://www.everfocus .com