The drivers for your TV tuner don't work in Windows 7 because they are not compatible with this operating system. If you have the setup package, right click it and select Troubleshoot Compatibility and use the recommended settings. Once this process is finished go to Device Manager (Start > right click computer > Properties) and manually update the driver for your TV tuner. Right click the item in device manager and use Update Driver. Point the installer to the path of installation (usually Program Files) and accept the driver installation. If you're lucky, it will work and you can use the TV tuner in Windows 7.
