Ethel's correct but just a word of caution:
If your 17 year old TV has got a Scart socket then any Freeview box will work. If not, you need to get a box with an RF modulator built in so that you can connect the box to the TV aerial socket. (NB: All Freeview boxes have an 'aerial out' connector but, in the vast majority of cases, these just provide 'RF feedthrough'. i.e. the only thing that comes out of the connector is a copy of the signal which feeds along your aerial cable without a Freeview box). Boxes with RF modulators are fairly rare and tend to be relatively pricey. (Typically around �70 - �80). There's a much cheaper box available, however, from here:
http://www.empiredirect.co.uk/Content/Products/details/i ndex.asp?modelcode=INV-IDL3000T&dt=Televisions&s t=Freeview+Digital+Box&make=Inverto&bhcp=1
Chris