For many people, the Hauppage card makes a great deal of sense. If your analog TV reception is good (or you are a cable subscriber), then the Hauppage card is the card to get. In my case, I am only recording over-the-air broadcasts and my analog reception is bad, so the Hauppage card would not be helpful to me.
I wish I could use a slower CPU. I need the full CPU for playback only because the nVidia acceleration is not all that reliable on AMD64. If I had gone the Intel route, I could probably use a slower CPU just because my nVidia card would offload some of the video playback processing. (Why, oh, why, did I let my friends talk me out of a Dothan core?)
I'm willing to bet that the differences between my relatively expensive system and your inexpensive system is (a) I can record and play back HD, and (b) the hardware looks better. For many people, or for somebody who wants to dip a toe into the water, there is no need to build a system totally from scratch like I did.