Think of it this way.... the signal is transmitted to the receiving device in a compressed format, be it OTA or from your cable/sat company. That bitrate is at BEST 18-19Mbps (and in some cases drastically less). In that compressed format, it is not difficult for current equipment to handle. If you have a PVR, then it is stored still compressed on it. If you have a firewire output then the stream the comes out of the firewire port is still compressed. It is when it gets to the point where the stream is passed to the component or DVI output that it gets uncompressed. And when that happens, it blows up like a balloon. Analog output is smaller than digital, but still hugely more data than in the previous steps.
So, looking at current hardware... if you have a DVR from your cable company that has firewire outputs, then that's great. It can take the still compressed signal that your cable company sends it and pass it out of the firewire port. Typically this can only be done to 5c compliant devices. No current satellite receivers have firewire output natively (the Dish 921 had the port, but never enabled it). There are 3rd party modifications that can add firewire and USB ports to certain satellite hardware, but the Voom receivers are architected in a way to prevent that.
Now, back to the original point... capturing the data to an HTPC. The only reasonable way to do this is to take the component out signal and convert it to SDI, then capture the SDI signal. This takes some very expensive equipment, and a lot of storage space. You also have to spend a fair bit of time afterwards manipulating it to a useable format. Not really a PVR type solution, and very very expensive.
-MP
