No POST beep and no video

I've just put together a new system using an existing working ATX case with a new tcommate K7TA-H mobo that I purchase 2 years ago from Geeks.com.
AMD Athlon 1200, 200FSB. After connecting everything - CPU and fan,AGP GeoForce4 MMX420, hard drive, cd rom, floppy drive, all front panel connectors - on first boot I could see keyboard lights flashing, cd rom light, cpu fan working, front panel lights working, hear hard drive spinning - but no POST beep nor any video. I thought the video card was bad - so installed another AGP card. Still no video. I then installed a PCI video card - still no video. I pared it down to just the PCI video card and power switch, and speaker switch (which I connected in the only two ways it could go on the front panel connector - in case that was a problem). I tried another loose speaker. Still no POST beep or video. I double checked the FSB jumper, I cleared the CMos jumper. I have all three memory slots filled with 256/128/128 PC 133 Dimms. Should I just use one slot of memory to start off?

What else is there to do? Is this a bad mobo? You can see the specs on this site:
http://tekgems.com/Products/et-9955-mbb-k7ta-h.htm
A pdf of manual here:
http://www.bare-bone.com/download/ [...] k7ta10.pdf

I checked the HSF - I had it on wrong. : (
The processor can only go in one way and that slipped in easily. Turned HSF around and reattached. Still no beep. I didn't force anything...honest! Maybe the CPU is bad. I think it was used. Can't remember. Is there a way to test the CPU?

Thanks