Well it turns out my problem was user error.. I had no idea there was an Intensity control panel to adjust the input/output settings. :S
I can now get a signal from my 360 and record just fine in SD, but I have just put together a RAID 0 so I can capture in HD. My problem now seems to lie with the control panel settings themselves. When I set the input processing to “off” to be able to capture in HD, I get no signal. I’m not running Windows on the array, but I didn’t think that would affect the viewing of the source video – I have the settings targeting my striped array for recording. Any advice?