Wires and delicate electronics need to be kept away from young children for a long time unless you're fond of frequent replacement and missing equipment. And of course there is the risk of the child getting hurt.
The most expensive answer is to replace the furniture. Many companies make entertainment centers like this one from Ikea. It hides all the equipment and wires and secures a flat planel from tipping over.
Wires from speaker systems can be routed through walls or hidden.
Barriers to access like baby gates work as short term solutions, but I haven't met anyone who tried it and was satisfied for more than a week.
Earthquake kits do a good job of keeping things from tipping over, but don't protect the wires or the electronics from poking and innappropriate usage.
Remote controls are a frequent target of young hands. They see us play with them all the time so it is only natural that baby wants to see what the fun is all about. If you have the typical home theater, you probably have accumulated 5 or 6 and keeping them all safe is tricky. Replacing them is a powerful universal remote like a Harmony can make life easier. Plus they're kind of awesome.
The lowest cost approach is to take away some items and pack them away until your child is older. There is life without television after all. :)