The most cost effective way to use the PC as a PVR is either SD(I know i know) OR Analog HD(1080i) with component video.
If you MUST use HDMI, you will need a drm/hdcp stripper and those are getting fewer and fewer now days. When HDMI came out many splitters had a side effect of passing the signal without the HDCP(DRM. Trust me, I wish I had one too
). This has since been corrected on most devices.
One of the more known solutions is/was the HDfury(it went to analog still). Many users like it, but many have also had issues(it was powered by the HDMI port, so that may have been one issue).
Going much further then this starts to get into a grey legal area that the forums frown on.