I don't know of ANY tv card that comes with a SCART input - or at least his was the case a while ago. There is no S-video out on the HC box and if you output S-video via the SCART connection it doesn't work and you just get a black and white image. So you will need to get a SCART to Composite/AudioL/AudioR (3 phono jacks) type lead and use the composite video in on the tv card.
I hadn't appreciated that you wanted to be able to connect the PC AND the TV. I can see a few options, you may be able to get a TV-card with a loop through (i.e. input and output) on the same card. You may need to get 2 tv cards, one to input to the PC and one to output to the tv. Alternatively, because SCART connectors are bi-directional you can actually use the input SCART on the HC box as an output - the image is not quite as good but is OK, in which case the TV would connect to the output of the HC box and the PC to the input of the HC box.