DVI to HDMI not working-- Can't detect monitors

I bought a DVI to HDMI cable to hook up to my Vizio LCDHD (VX32L) to my Power Mac G4 (450 MHz) with VGA and a DVI outputs on the video card (ATY,Rage128Pro). When I boot up the computer the apple screen pops up on the LCDHD then immediately disappears. I then unplug the DVI cable and plug back in my old monitor, nothing happens, then a restart brings back the old CT. When I plug in both monitors, I get nothing on both.

It seem like the card doesn't support two monitors because my computer doesn't show the detect display or mirroring options, its like the DVI jack stops working. I tried using my old monitor with the RGB PC jack on the video card to set up my specs with DisplayConfigX but that doesn't seem to help. Will a new video card be in order?

Another thought: I can borrow a LCD monitor, hook it up to the DVI and try to set up the specs with DisplayConfigX, if I get no image on the LCD monitor, then my card is fried.

Is this a waste of time considering the lack of power of the G4? I wanted it to be use primarily for recording TV programs off a USB HD tuner* and replaying on the LCDHD.

*I know I'll have to install a USB 2.0 card in order to get the tuner to work.

Machine Name: Power Mac G4 (AGP graphics)
Graphics/Displays: ATY,Rage128Pro
System Version: Mac OS X 10.4.11 (8S165)
Machine Model: PowerMac3,1
CPU Type: PowerPC G4 (2.9)
Number Of CPUs: 1
CPU Speed: 450 MHz
L2 Cache (per CPU): 1 MB
Memory: 1.25 GB
Bus Speed: 100 MHz