I'm really stumped on what hardware I actually need to get for my old computer to turn it into a PVR. I've been browsing the various MythTV setup descriptions, but I'm a total newbie when it comes to this, and it gets a bit confusing.

I don't need a TV tuner (I don't think), I have a satellite decoder, and what I want to be able to do is record whatever is being displayed on the TV. I also want to be able to record TV and watch at the same time. All the mythTV setups reckon I'd need two TV tuner cards to do this. I spoke to my local online hardware shop and they suggested the following graphics card:

INNOVISION Inno3D Video Card Nvidia GeForce 6600GT PCI-e X16 (128MB / 128bit DDR, 300MHz/550MHz, DVI, VIVO )

Now, I won't be able to use this, because the machine I'm wanting to turn into a PVR box is a PIII 1.13 GHz with 512Mb RAM and an AGP 4x slot. It's currently running Kubuntu 7.04.

Could someone enlighten me on the hardware (or cabling) I would need to achieve my aims, namely:
1) Record the television signal at the same time as watching it (bearing in mind I don't really need to decode any signal, I have an external satellite decoder, this one: http://www.dstv.com/main.aspx?ID=256 It's output is RCA cable type)
2) Play DVDs on the computer and have them displayed on TV (normal svideo out graphics card should be fine here right?)

Thanks,
Dave

The video card you are looking at is a good choice, as nVidia has been very good at supporting Linux and svideo out. But it is not enough to connect to your tuner. MythTV recommends a tuner card for video capture purposes, and you will need one for that. I recommend the WinTV 150 PVR for this, as it has a remote and an IR Blaster that can control your tuner for you, similar to how Tivo works (I also have a Tivo). While you won't be using the Tuner card to actually tune in the channels, it will receive and encode the video signal, without a lot of cpu overhead.