When I want to watch TV, I get a message that says,
"Please ensure that both the tuner card and a valid tuner card driver are installed." What can I do to solve the issue.

I scanned a the computer at gateway.com and gave me the following Information:

Operating System

Windows XP SP1 (Windows XP 5.1.2600 Service Pack 1)
Original setup date: 10/1/2009
DirectX Version: 5.3.0000001.0904 built by: private/Lab06_dev(DXBLD00)
SWAP FILE DISABLED
File cache managed by Windows

Try doing a windows update should be service pack 3.

and go into device maneger and check the driver for the card is installed.

yea what popeye said and if that doesnt work. after updating everythin try gettin a new card u might have gotten a dead one. or is not compatible with your pc.