Sam's problem is that despite our help OTA doesn't work well for him, but he does have access to QAM programming via his local cable company. Normally this wouldn't be a problem but even though QAM is supported by his capture card he still can't record and stream HD to his Xbox 360. Yes Sam the new Series3 TiVo supports QAM and OTA channels.
Unfortunately I have bad news, there is no good solution until Microsoft decides to support QAM in MCE. There are two work around neither are very elegant.
One is to use a 3rd party recording software to record your QAM programming and save the files into your MCE's My Movies folder. This doesn't integrate with MCE very well, but it's still possible to stream to your Xbox 360 as long as the files are MPEG2. Of course there will be no meta data to help identify the files so hopefully the software labels them well. The biggest challenge is finding cards that play well together when they are both installed on the same MCE PC.
The second option works better, but is more expensive. First contact your cable provider and request a STB with a functional 1394 port. Next verify that your MCE PC has a 1394 port or buy an optional PCI card. Then buy an additional SD capture card (MCE supports 2). Once you have all the hardware connected you install some 3rd party software that allows you to record non-encrypted HD content via 1394 using MCE. The method records both SD and HD material at the same time and as a result you get a SD version instead of a HD version of encrypted content. The cool part is that the HD material has full meta data and is well integrated with MCE. The bad news is that in most areas the only non-encrypted channels are the same ones you can get for free OTA.