Is it possible to use my laptop as a remote control for my TV?

There aren’t any real software offerings in this department because most infrared ports on laptops have very very short range (about 1 meter). There were originally for transmitting data from laptop to laptop, but this has since been replaced by wireless communications like Wifi.

If you want a better way to control your home theater system your best option is Logitech’s Harmony Remote Contorls: http://www.logitech.com/index.cfm/remotes/universal_remotes/&cl=us,en