You can have analogue and digital tv cards on one machine but if you intend to use it through windows media centre it is involved and requires various registry hacks. In fact it's difficult however you try it although it can be done. The best bet is freeview in the UK - you can find out more at the greenbutton.com. If you wanted to add a tv card to a laptop, I don't think anyone make a pci version - no room
However, there are various usb cards - Hauppauge is probably the best known. Just plug it in, load the software and off you go. However, the supplied aerials are rubbish. You wil only get a reliable signal by using the household aerial.
This is what you need:
http://www.hauppauge.co.uk/pages/pro...vatdstick.html