Alrighty, here's how to update the connections.
On the back of the DVD player, there are three cables connected to component video outputs. Those are labeled "Y", "PB", and "PR" and are color coded.
The first thing to do is to simply disconnect those from the DVD player and connect them to the "COMPONENT VIDEO - MONITOR OUT" jacks on the receiver that are also labeled "Y", "PB", and "PR" and are color coded. The cable connectors also appear color coded in your picture, so I think that you won't have any trouble making that switch.
Next, you could hook up your Xbox 360 to one set of the COMPONENT VIDEO inputs on the back of the receiver, and hook up the analog audio (red/white connectors) to one of the audio inputs on the receiver ("V-AUX", for example). Remember that you'll need to assign the component video inputs to the correct source selection ("V-AUX" in this example).
The one remaining connection to make is the video connection from the DVD player to the receiver. For that, you'll need another set of three cables to connect the component video outputs from the DVD player (the green, blue, and red connectors) to the receiver. You definitely don't need to use Monster cables like were used (probably recommended by the Best Buy salesperson). You can get those cables made by different manufacturers for much less money at places like Monoprice.com or other stores that will work just as well. If you want some suggestions, just let us know. If you have three RCA cables around, you can use those, too. You do want to use video cables instead of audio cables because video cables have more shielding around the wire, but you can always swap the cables out later if needed.