A good playback test/application is Media Player Classic, or it's HC edition since it includes all of it's own internal filters. You can try it without messing up any other players on the PC. It even has Quicktime and RealPlayer plugins so you don't have to install either to play their content. A standard DVD player software might not be able to do HD.
The Hauppauge software decoder (hcwSMD07) can be used by Window's Media Player for ATSC but might require adjusting filter merits, always a touchy proposition. I only have Media Player up to v9 because GB-PVR (third party software for the Hauppauge cards) won't install without it. (and Windows2000 can't go to v10)
You would not just be doing a simple resizing, but a serious transcoding to convert HD to SD (or avi, etc). I use gui4ffmpeg myself to convert to standard DVD 720x480. There are others.