You need a Digital + Analogue TV PCI card or dongle for Freeview - you can also buy satellite and cable versions.
Look for DVB-T logos for Freeview (the T represents Terrestial i.e. digital signals are received via a wideband terrestial TV aerial).
If you are thinking of buying such a device you'll have to ensure that you can get a decent TV aerial signal to it.
An example of a USB Digital Video Broadcast-T stick can be found here: