The more the merrier.
How many GBs would we need for, say, 6 hours of good quality video?
Depends upon several variables, but most notibly at what resolution your capturing and what you define as a good quality picture - a purely subjective issue so there is no definitive answer. You can, however, get some idea of your storage needs by considering the following:
Not including audio (which btw doesn't account for very much), an uncompressed analog NTSC video signal (which we'll define for argument sake as being 720x480 - note: its not the true resolution but its close enough for purposes here) runs at ~20MBps = ~70GB per hr. Which, obviously, means that a 120GB drive would allow you ~1.75 hrs of record time.
However, no one in their right mind should use uncompressed considering that if you use a loseless (ie. no quality differnece from uncompressed stream) video codec like Huffyuv, the transfer rates are approximately cut in half ( say ~35GB per hr - actually, you can do even better with huffy, but we'll leave it at this). So the same 120GB HDD would give you close to around 3.5 hours. If the material you are recording is something you wish to archive, then you want to use a loseless codec. That way, you can doing all your editing (cut out commercials etc.), apply any filters you which to use, and save it without taking a generation loss in picture quality before you (if you want to for space reasons) render it to another format such as Divx, Xvid....
For things such as PVR, Tivo/Replay, DVCR or whatever you want to call this type of functionality, for shows your just going to watch once and then record over (and are not overly concerned about obtaining the best possible picture) then your looking at MPEG2 and perhaps even Divx or the like. For lousey (as in some picture information is discarded) codecs such as these, the storage requirements are going to depend upon the bit rates you set them to operate at....the higher the rate the larger the captured file, conversely, the lower the rate the more the picture is compressed and the smaller the resultant file. Resultant picture quality will depend a fair amount upon the chipset your capture card uses, better cards will give you a petty descent picture. With avg to higher quality Mpeg2 capture settings, your looking at around 5GB/hr. Divx considerably less (if you can find a SMP capture app those two cpu's of yours should be able to handle this without any problems)............so as you can see, something like a 120GB drive would give you many many hours of PVR capturing and storage capabilities.
Is it worth while to get something like an ATI All in Wonder, or is a separate TV tuner/capture card needed?
Many variables here too and your decision really depends upon what you like to do with your system and your budget. Seperate tuner/capture cards are nice in that they you can upgrade your video card more frequently than you might otherwise. AIW are very nice too and easy to use, and probably less likely to have any sort of strange compatibility problems with other hardware. I'm pretty sure that Mercutico has a Radeon 9700AIW, so he could probably answer any questions you have about that card and supporting software etc. In the mean time, questions you want to ask your self are: Are you a gamer? Do you upgrade that often? Do you want quality TV-out? etc etc
You'll have to do some homework on the potential cards that your looking at ie. what chipset does the card use, what's its application support like, what about driver support (vfw or WDM) etc etc....Actually, driver support is a big thing with capture cards (read the source of most aggrevation)... you can have the fanciest piece of hardware, but without good drivers it will be utterly useless. Drivers (vfw or WDM) will also determine which apps you will or won't be able to use succesfully.
One last thing is that the introduction of digital television is (very slowly) begining to change the landscape in tv-tuner world, so pending upon your ability to recieve terrestrial (over the air aerial reception) or satalite/cable reciever signals, your descion may differ....just something to think about.
I would advise you stay away from the BT878 based cards [1) newer and better quality stuff is available, 2) although a few have pretty good quality, with the majority of these cards the quality lacks]....however, that said, if you just want basic vcr record and watch once function, then one of these cheapies would probably fit the bill (plus there is a good 3rd party driver for it available......
How many millions of dollars will this cost us?
A lot less than what you probably think.
