Using Webcam for security at office

Hi friends,

I want to connect 3 webcams to my PC at different places in my office. regular security camera cost a bit more. i want a cheap solution for this. can anyone help me with what i need. i wont be using internet or ftp uploading. just want the video to be displayed on screen...

My questions are:

1. how to extend the webcam wire length from default to around 100 feets
2. can i use c5 extender?
3. any other hardware or software needed?

Awaiting your replies and suggestions.

Thanks in advance
Rajkiran Singh