What would be the preferred version of the Hauppauge PVR card to get; I know that earlier that the PVR-150 card the one to pick due to quality of the output from the chip used. But, what is last said here? Also, would the choice of card be the same if a dual card system is to be put together?
Well, it depends. If you mostly want to digitize old VCR material, the 150 is probably the best choice because it can deal better with instable video sources. However, use S-Video instead of Composite whenever possible. If the goal is mainly watching TV, I would prefer a 250 revision 2 or later. But since the 250 has basically been discontinued by Hauppauge, it's hard to get a new one these days. The 350 has this TV-out feature, but it is implemented somewhat halfway and not many people use it. Also it consumes a lot of power, produces a lot of heat and is the oldest and most expensive (single) tuner card. Technically it's similar to the 250. It has FM radio functionality, which on the 150 and the 250 is only present in the MCE versions.
If you want a dual system a 500 could be used. It behaves like two 150s, but only one of them has an FM radio. There were some serious problems with 500 cards, when Hauppauge used bad tuner modules by Samsung. But I think they have switched back to Philips and replaced a lot of cards sold in th U.S.. European (PAL) cards were not affected AFAIK.
The EmperoarTV application is not really prepared to handle mutiple tuners. However, you can install two instances and/or use one card for watching and one for recording.
Bottomline: it's hard to suggest something. All cards can produce pretty decent results. However, they all have strong and weak points.