well, the 3 computers i use the most would be my desktop with an overclocked q6600 and nvidia gtx 260, my htpc with an athlon x2 3800+ and an nvidia 8600gt, and my netbook which has an AMD E350 and a radeon 6310.
on my desktop im basically doing what the guide suggests. well, im exactly doing what it suggests actually.
on my htpc, the video card doesn't have enough memory for madvr, so im stuck using lav cuvid for decoding and ffdshow for hq rgb conversion. Why don't I get a new graphics card your wondering? well, i need component video out. and everything nowadays is hdmi, so i have to wait till i upgrade my tv first.
on my netbook, i use dxva for performance and battery life reasons.
If I had to suggest a new card, I would probably suggest a radeon 6450 or nvidia gt 520 if deinterlacing 1080i isnt that important to you and you have a good enough cpu for yadif and frame doubling and decoding. If you need high quality 1080i deinterlacing, nvidia gt 440 with gddr5.