Which accessories are a 'most have' for connecting my TV to a desktop pc?

You'll need:
•VGA cable
•S-Video Audio to 3 RCA Type Adapter Cable
•HDMI cable
•DVI cable
Check the connection options on your TV. If your TV has a VGA connection slot, plug the TV into the computer with a VGA cordlike a computer monitor. Connect one end of the VGA cable to the back of the computer and the other end to the TV. Switch between normal TV viewing to displaying your computer on your TV by selecting the proper mode from the remote control, some remotes will mark the proper mode as "VGA" while others will label it "Computer" or "PC."
Check the back of your computer to see if you have an S cable slot. Connect S cable portion of the S-Video Audio to 3 RCA Type Adapter Cable to the computer and plug in the green audio plug to the audio port of the PC. Plug the red white and yellow RCA cables into the matching colors of the RCA slots on the TV. With this method you will need to switch modes from TV to video.
Check the back of the computer and TV for either DVI or HDMI slots. The slots on your computer must match, you cannot connect a DVI to a HDMI. Plug one end of the corresponding cable into the the back of the TV and the other end into the computer. Choose the correct program mode, HDMI or DVI, from the remote to view the computer from the TV.