If your computer graphic card has a dual SVGA (or a SVGA and HDMI) connectors, you can simply use a SVGA cable to connect your LCD TV. If you want to see the TV just use the TV tuner or sat/cable tuner (if you have any). If you want to see anything from your computer on the TV screen just use the PC input from the remote control.

Berfore that you have to set up the system (better if you hire an expert). I can tell the basics, but each combo Graphic card + TV Brand is different.
First, turn on the TV before the PC, to let the graphic card aware of another device plugged.
Then, from your windows desktop you can activate hydravision or nView (for ATI or nVidia brands).
When you can see 2 monitors from your settings you can adjust the resolution of the TV (usually widescreen TV is 1360x768).
If you select PC from the remote control you can see the computer screen on the TV, and now it's the tough part... You have to choose the mode, "clone" is the same of your monitor, i like to use an "extended desktop", and i just drag on the TV screen what i want.

I have a Samsung LCD 40", my main use is for DIVX movies/TV shows, so i have dragged Windows media player on the TV, so when i open a video on the computer i can see it on TV. in this way i can see both TV and monitor (looking sports on TV while playing poker or reading the board on PC).