I have a Toshiba Satellite L305D-S5934. I'm trying to connect it to my TV to watch videos. The TV has HDMI and S-Vid ports; the laptop only has USB and RGB monitor (VGA?) ports. What kind of cable/adapter(s) do I need to get?

You can buy an HDMI to VGA connector for about 10 dollars at best buy or ciruit city. However depending on screen resolutions you may not be able to use the entire TV screen, but it will be good enough to watch movies.

Another cable your going to need is a audio adapter plug to go from laptop to your TV. Your vga (rgb) does not carry audio.

Another solution may be to upgrade your laptop to a newer one.