Creating the “you can walk into this picture” feel is mostly about technique, a nice DSLR and some nice lenses help but aren’t necessary. 95% of creating the look that you can walk into a photo is creating depth; you have to create layers in the shot. You have to have fore, middle, and background layers that are distinct. You create the layers with light and the elements in each layer.
This don’t mean you have to set up a bunch of lights, you can work with the available light. The easiest way to do it is to use light and shadow or sun and shade. Use the shadows and highlights to create texture in the scene, the texture gives the appearance of separation between objects. If there is no texture, no apparent separation of the objects in the scene it will look flat.
Another way to create depth is with perspective, think of rail road tracks that appear to converge or how a distant mountain only looks as tall as a tree. Compose you shots so that the elements within the frame create the same kind of effect. Also use your depth of field, the human eye can not focus over a great distance, it can however refocus much faster than any camera. As your eyes scan a scene in the real world they are constantly adjusting making every thing seem to be in focus. Pick an object in the middle of the room to look at, and without moving your eye notice that everything around that object starts to more out of focus the farther from the center you get. Focus on your subject and let the focus in the rest of the scene trail off as you move farther away from your subject.
There are a lot of different ways to create depth in your photos and these are just a couple. The biggest thing is practice, practice and more practice.
Here are a couple of example of the techniques I mentioned above.