I have a PowerMac G4: PowerPC7400, 2x500MHz, 1GB Ram, ATI Rage 128PRO 16MB videocard, Mac OS X 10.4

I want to know if it is even possible to turn this PowerMac into a DVR by connecting my coax cable (which I believe is a mix of analog/digital cable signals)

WHAT HARDWARE WOULD I NEED?
WHAT SOFTWARE WOULD I NEED?

Please be SPECIFIC.....