New monitor/tv?

I am considering replacing my near 10 year old 21” monitor and older similar sized TV which sits next to it, with a state of the art flatscreen mounted on the wall, but have no idea what to go for, i.e. what type, specs. and features, suggestions please……

Also, do I go for a monitor or TV with VGA input?
Can the TV be watched, and PC applications be done at the same time?

I am UK based and wish to view Freeview (digital service) so I am also considering a TV card for the PC.
How do I check that my motherboard in my ~4 year old PC, with onboard graphics (http://www.asrock.com/mb/overview.asp?Model=P4VM890) will be compatible with a new monitor & tv card?