yeah you can.
If your buying a new LCD tv then it will have a HDMI socket(or 2 depending on the set) so you connect your ps3 into that, and then new LCD tv's also come with a VGA connection on the back of the tv, so thats where you connect your pc into

Note that you will need a cable to connect the pc and tv together, if you ask in a store like Currys etc or go online to Ebuyer you will find them on there cheaply enough.